xfs: remove the unused XFS_QMOPT_DQLOCK flag

The XFS_QMOPT_DQLOCK flag introduces major complexity in the quota subsystem
but isn't actually used anywhere.  So remove it and all the hazzles it
introduces.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Felix Blyakher <felixb@sgi.com>

fs/xfs/xfs_quota.h

@@ -185,7 +185,6 @@ typedef struct xfs_qoff_logformat {
  * to a single function. None of these XFS_QMOPT_* flags are meant to have
  * persistent values (ie. their values can and will change between versions)
  */
-#define XFS_QMOPT_DQLOCK	0x0000001 /* dqlock */
 #define XFS_QMOPT_DQALLOC	0x0000002 /* alloc dquot ondisk if needed */
 #define XFS_QMOPT_UQUOTA	0x0000004 /* user dquot requested */
 #define XFS_QMOPT_PQUOTA	0x0000008 /* project dquot requested */