drm/amdgpu: fix kernel-doc warnings on non-kernel-doc comments

drm/amdgpu: fix kernel-doc warnings on non-kernel-doc comments

Don't use "begin kernel-doc notation" (/**) for comments that are
not kernel-doc. This eliminates warnings reported by the 0day bot.

drivers/gpu/drm/amd/amdgpu/gfx_v9_4_2.c:89: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
    * This shader is used to clear VGPRS and LDS, and also write the input
drivers/gpu/drm/amd/amdgpu/gfx_v9_4_2.c:209: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
    * The below shaders are used to clear SGPRS, and also write the input
drivers/gpu/drm/amd/amdgpu/gfx_v9_4_2.c:301: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
    * This shader is used to clear the uninitiated sgprs after the above

Fixes: 0e0036c7d13b ("drm/amdgpu: fix no full coverage issue for gprs initialization")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: kernel test robot <lkp@intel.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: "Pan, Xinhui" <Xinhui.Pan@amd.com>
Cc: Dennis Li <Dennis.Li@amd.com>
Cc: amd-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>