[XFS] Unwrap pagb_lock.

Un-obfuscate pagb_lock, remove mutex_lock->spin_lock macros, call
spin_lock directly, remove extraneous cookie holdover from old xfs code,
and change lock type to spinlock_t.

SGI-PV: 970382
SGI-Modid: xfs-linux-melb:xfs-kern:29743a

Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Signed-off-by: Donald Douwsma <donaldd@sgi.com>
Signed-off-by: Tim Shimmin <tes@sgi.com>
diff --git a/fs/xfs/xfs_ag.h b/fs/xfs/xfs_ag.h
index 9381b03..61b292a 100644
--- a/fs/xfs/xfs_ag.h
+++ b/fs/xfs/xfs_ag.h
@@ -193,7 +193,7 @@
 	xfs_agino_t	pagi_count;	/* number of allocated inodes */
 	int		pagb_count;	/* pagb slots in use */
 #ifdef __KERNEL__
-	lock_t		pagb_lock;	/* lock for pagb_list */
+	spinlock_t	pagb_lock;	/* lock for pagb_list */
 #endif
 	xfs_perag_busy_t *pagb_list;	/* unstable blocks */
 	atomic_t        pagf_fstrms;    /* # of filestreams active in this AG */