drm/amd/display: Remove outdated register for dcn3+

[Why & How]
Remove MPCC_OGAM_LUT_RAM_CONTROL register which is outdated.

Reviewed-by: Nevenko Stupar <Nevenko.Stupar@amd.com>
Reviewed-by: Martin Leung <Martin.Leung@amd.com>
Acked-by: Wayne Lin <wayne.lin@amd.com>
Signed-off-by: Tse Kaitlyn <Kaitlyn.Tse@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>