drm/amdgpu: fix vkms crtc settings

otherwise adev->mode_info.crtcs[] is NULL

Signed-off-by: Flora Cui <flora.cui@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amdgpu: replace dce_virtual with amdgpu_vkms (v3)

Move dce_virtual into amdgpu_vkms and update all references to
dce_virtual with amdgpu_vkms.

v2: Removed more references to dce_virtual.

v3: Restored display modes from previous implementation.

Signed-off-by: Ryan Taylor <Ryan.Taylor@amd.com>
Reported-by: kernel test robot <lkp@intel.com>
Suggested-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amdgpu: create amdgpu_vkms (v4)

Modify the VKMS driver into an api that dce_virtual can use to create
virtual displays that obey drm's atomic modesetting api.

v2: Made local functions static.

v3: Switched vkms_output kzalloc for kcalloc.
Cleanup patches by moving display mode fixes to this patch.

v4: Update atomic_check and atomic_update to comply with new kms api.

Signed-off-by: Ryan Taylor <Ryan.Taylor@amd.com>
Reported-by: kernel test robot <lkp@intel.com>
Suggested-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>