xfs: untangle SYNC_WAIT and SYNC_TRYLOCK meanings for xfs_qm_dqflush

Only skip pinned dquots if SYNC_TRYLOCK is specified, and adjust the callers
to keep the behaviour unchanged.

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

diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c
index 25d7280..9aef727 100644
--- a/fs/xfs/xfs_dquot.c
+++ b/fs/xfs/xfs_dquot.c
@@ -1169,7 +1169,7 @@
 	 * If not dirty, or it's pinned and we are not supposed to block, nada.
 	 */
 	if (!XFS_DQ_IS_DIRTY(dqp) ||
-	    (!(flags & SYNC_WAIT) && atomic_read(&dqp->q_pincount) > 0)) {
+	    ((flags & SYNC_TRYLOCK) && atomic_read(&dqp->q_pincount) > 0)) {
 		xfs_dqfunlock(dqp);
 		return 0;
 	}