drm/amd/display: Check SCRATCH reg to determine S3 resume.

drm/amd/display: Check SCRATCH reg to determine S3 resume.

Use lid state only to determine fast boot optimization is not enough.
For S3/Resume, due to bios isn't involved in boot, eDP wasn't
light up, while lid state is open, if do fast boot optimization,
eDP panel will skip enable link and result in black screen after boot.
And becasue of bios isn't involved, no matter UEFI or Legacy boot,
BIOS_SCRATCH_3 value should be 0, use this to determine the case.

Signed-off-by: Yongqiang Sun <yongqiang.sun@amd.com>
Reviewed-by: Charlene Liu <Charlene.Liu@amd.com>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>