GFS2: Bring back lvb-related stuff to lock_nolock to support quotas

The quota code uses lvbs and this is currently not implemented in
lock_nolock, thereby causing panics when quota is enabled with
lock_nolock. This patch adds the relevant bits.

Signed-off-by: Abhijith Das <adas@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>