drm/amdgpu: fix drm-next merge fallout

That hunk somehow got missing while solving the conflict between the TTM
and AMDGPU changes for drm-next.

Signed-off-by: Christian König <christian.koenig@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220503063613.46925-1-christian.koenig@amd.com