drm/amd/display/dc/dce120/Makefile: Ignore -Woverride-init warning

drm/amd/display/dc/dce120/Makefile: Ignore -Woverride-init warning

This file uses a complex abstracted set of hierarchical macros to
setup its applicable register lists within constant structures.
However in the case of TMDS_CNTL we wish to mark it as not applicable
for this use-case.

One method would be to de-const all of the definitions and users, then
manually zero out TMDS_CNTL from the list.  Another would be to create
a new set of hierarchical macros to omit TMDS_CNTL entirely.  Both
would entail a great deal of unnecessary changes and maintenance
burden.

Instead, let's just silence the warning.

Fixes the following W=1 kernel build warning(s):

 drivers/gpu/drm/amd/amdgpu/../display/dc/dce120/dce120_resource.c:277:15: warning: initialized field overwritten [-Woverride-init]
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce120/dce120_resource.c:281:2: note: in expansion of macro ‘stream_enc_regs’
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce120/dce120_resource.c:277:15: note: (near initialization for ‘stream_enc_regs[0].TMDS_CNTL’)
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce120/dce120_resource.c:281:2: note: in expansion of macro ‘stream_enc_regs’
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce120/dce120_resource.c:277:15: warning: initialized field overwritten [-Woverride-init]
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce120/dce120_resource.c:282:2: note: in expansion of macro ‘stream_enc_regs’
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce120/dce120_resource.c:277:15: note: (near initialization for ‘stream_enc_regs[1].TMDS_CNTL’)
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce120/dce120_resource.c:282:2: note: in expansion of macro ‘stream_enc_regs’
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce120/dce120_resource.c:277:15: warning: initialized field overwritten [-Woverride-init]
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce120/dce120_resource.c:283:2: note: in expansion of macro ‘stream_enc_regs’
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce120/dce120_resource.c:277:15: note: (near initialization for ‘stream_enc_regs[2].TMDS_CNTL’)
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce120/dce120_resource.c:283:2: note: in expansion of macro ‘stream_enc_regs’
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce120/dce120_resource.c:277:15: warning: initialized field overwritten [-Woverride-init]
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce120/dce120_resource.c:284:2: note: in expansion of macro ‘stream_enc_regs’
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce120/dce120_resource.c:277:15: note: (near initialization for ‘stream_enc_regs[3].TMDS_CNTL’)
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce120/dce120_resource.c:284:2: note: in expansion of macro ‘stream_enc_regs’
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce120/dce120_resource.c:277:15: warning: initialized field overwritten [-Woverride-init]
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce120/dce120_resource.c:285:2: note: in expansion of macro ‘stream_enc_regs’
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce120/dce120_resource.c:277:15: note: (near initialization for ‘stream_enc_regs[4].TMDS_CNTL’)
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce120/dce120_resource.c:285:2: note: in expansion of macro ‘stream_enc_regs’
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce120/dce120_resource.c:277:15: warning: initialized field overwritten [-Woverride-init]
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce120/dce120_resource.c:286:2: note: in expansion of macro ‘stream_enc_regs’
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce120/dce120_resource.c:277:15: note: (near initialization for ‘stream_enc_regs[5].TMDS_CNTL’)
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce120/dce120_resource.c:286:2: note: in expansion of macro ‘stream_enc_regs’

Cc: Harry Wentland <harry.wentland@amd.com>
Cc: Leo Li <sunpeng.li@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: amd-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>