Atomic doesn't really work without universal planes anyway. But make
sure that evil userspace doesn't pull the kernel over the table
because we didn't consider a cornercase that just doesn't make sense,
just for safety.
v2: Just force ->universal_planes to the same value to avoid imposing
restrictions on userspace.
Cc: Rob Clark <robdclark@gmail.com> Reviewed-by: Rob Clark <robdclark@gmail.com> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>