drm/amd/display: Query DC for gfx handling when setting linear tiling

drm/amd/display: Query DC for gfx handling when setting linear tiling

[Why]
Post-driver cases always use linear tiling yet gfx handling for this
case is improper, allowing for incorrect gfx structs to be populated and
used.

[How]
Query DC for the apporpriate linear tiling mode and populate the DCN
specific gfx version structs.

Reviewed-by: Dillon Varone <dillon.varone@amd.com>
Signed-off-by: Nicholas Carbones <Nicholas.Carbones@amd.com>
Signed-off-by: Chuanyu Tseng <chuanyu.tseng@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>