radeon: Split out ring locking and allocation

We need to handle the ring while we've already locked it, so split out
the allocation and commit functions in order to allow them to be used.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

diff --cc drivers/gpu/drm/radeon/radeon.h
Simple merge

diff --cc drivers/gpu/drm/radeon/radeon_ring.c
Simple merge