NFSv4.1/flexfile: ff_layout_remove_mirror can be static

Signed-off-by: NFengguang Wu <fengguang.wu@intel.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>

fs/nfs/flexfilelayout/flexfilelayout.c

@@ -183,7 +183,7 @@ ff_layout_add_mirror(struct pnfs_layout_hdr *lo,
 	return mirror;
 }
 
-void
+static void
 ff_layout_remove_mirror(struct nfs4_ff_layout_mirror *mirror)
 {
 	struct inode *inode;