xfs: split dquot buffer operations out

Parts of userspace want to be able to read and modify dquot buffers
(e.g. xfs_db) so we need to split out the reading and writing of
these buffers so it is easy to shared code with libxfs in userspace.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ben Myers <bpm@sgi.com>

diff --cc fs/xfs/Makefile
Simple merge

diff --cc fs/xfs/xfs_dquot.c
Simple merge

diff --cc fs/xfs/xfs_dquot_buf.c
Simple merge

diff --cc fs/xfs/xfs_log_recover.c
Simple merge

diff --cc fs/xfs/xfs_qm.c
Simple merge

diff --cc fs/xfs/xfs_qm.h
Simple merge

diff --cc fs/xfs/xfs_quota.h
Simple merge

diff --cc fs/xfs/xfs_quota_defs.h
Simple merge