[GFS2] gfs2_adjust_quota has broken unstuffing code

This patch combines the 2 patches in bug 434736 to correct the lock
ordering in the unstuffing of the quota inode in gfs2_adjust_quota and
adjusting the number of revokes in gfs2_write_jdata_pagevec

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