xfs: fix the comment of xfs_btree_get_iroot()

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>

diff --git a/fs/xfs/xfs_btree.c b/fs/xfs/xfs_btree.c
index eccc788..ae106f6 100644
--- a/fs/xfs/xfs_btree.c
+++ b/fs/xfs/xfs_btree.c
@@ -510,7 +510,7 @@
 }
 
 /*
- * Get a the root block which is stored in the inode.
+ * Get the root block which is stored in the inode.
  *
  * For now this btree implementation assumes the btree root is always
  * stored in the if_broot field of an inode fork.