drm/amd/display: Add Handling for gfxversion DcGfxBase

drm/amd/display: Add Handling for gfxversion DcGfxBase

[Why]
There is no way to set tiling in dml in the case that gfxversion is
DcGfxBase.

[How]
Where tiling is updated based on Gfx, add case for DcGfxBase and set
tiling to dml2_sw_linear.

Reviewed-by: Dillon Varone <dillon.varone@amd.com>
Signed-off-by: Nicholas Carbones <ncarbone@amd.com>
Signed-off-by: Wayne Lin <wayne.lin@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>