drm/amd/powerplay: remove set but not used variable 'vbios_version', 'data'

drm/amd/powerplay: remove set but not used variable 'vbios_version', 'data'

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/gpu/drm/amd/powerplay/hwmgr/smu7_hwmgr.c: In function smu7_check_mc_firmware:
drivers/gpu/drm/amd/powerplay/hwmgr/smu7_hwmgr.c:4215:11: warning: variable vbios_version set but not used [-Wunused-but-set-variable]
drivers/gpu/drm/amd/powerplay/hwmgr/smu7_hwmgr.c: In function smu7_get_performance_level:
drivers/gpu/drm/amd/powerplay/hwmgr/smu7_hwmgr.c:5054:21: warning: variable data set but not used [-Wunused-but-set-variable]

'vbios_version' is introduced by commit 599a7e9fe1b6 ("drm/amd/powerplay:
implement smu7 hwmgr to manager asics with smu ip version 7."),
but never used, so remove it.

'data' is introduced by commit f688b614b643 ("drm/amd/pp:
Implement get_performance_level for legacy dgpu"), but never used,
so remove it.

Reviewed-by: Evan Quan <evan.quan@amd.com>
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: zhengbin <zhengbin13@huawei.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>