drm/amd/display: enable S/G for RAVEN chip

drm/amd/display: enable S/G for RAVEN chip

enables gpu_vm_support in dm and adds
AMDGPU_GEM_DOMAIN_GTT as supported domain

v2:
Move BO placement logic into amdgpu_display_supported_domains

v3:
Use amdgpu_bo_validate_uswc in amdgpu_display_supported_domains.

v4:
amdgpu_bo_validate_uswc moved to sepperate patch.

Signed-off-by: Shirish S <shirish.s@amd.com>
Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>