xfs: fix the comment of xfs_mod_incore_sb_unlocked()

Signed-off-by: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
Reviewed-by: Mark Tinguely <tinguely@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

fs/xfs/xfs_mount.c

@@ -1083,7 +1083,7 @@ xfs_log_sbcount(xfs_mount_t *mp)
 }
 
 /*
- * xfs_mod_incore_sb_unlocked() is a utility routine common used to apply
+ * xfs_mod_incore_sb_unlocked() is a utility routine commonly used to apply
  * a delta to a specified field in the in-core superblock.  Simply
  * switch on the field indicated and apply the delta to that field.
  * Fields are not allowed to dip below zero, so if the delta would