drm/amdgpu: only allow scatter/gather display with DC

Check if DC is enabled before allowing scanout buffers
to be pinned in system memory.

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Alex Deucher 2018-01-12 14:56:49 -05:00
commit 2c9c178b7d