drm/amdgpu: Update pitch on page flips without DC as well

DC already handles this correctly since amdgpu minor version 31. Bump
the minor version again so that xf86-video-amdgpu can take advantage of
this working without DC as well now.

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Michel Dänzer <michel.daenzer@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>