drm/edid: add a quirk for two LG monitors to get them to work on 10bpc

drm/edid: add a quirk for two LG monitors to get them to work on 10bpc

[ Upstream commit aa193f7eff8ff753577351140b8af13b76cdc7c2 ]

The LG 27GP950 and LG 27GN950 have visible display corruption when
trying to use 10bpc modes. So, to fix this, cap their maximum DSC
target bitrate to 15bpp.

Suggested-by: Roman Li <roman.li@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>