NFS: Create a have_delegation rpc_op

Delegations are a v4 feature, so push them out of the generic code.

Signed-off-by: Bryan Schumaker <bjschuma@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index f729698..0f0b928 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -1457,7 +1457,7 @@
 	if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode)
 				|| S_ISLNK(inode->i_mode)))
 		invalid &= ~NFS_INO_INVALID_DATA;
-	if (!nfs_have_delegation(inode, FMODE_READ) ||
+	if (!NFS_PROTO(inode)->have_delegation(inode, FMODE_READ) ||
 			(save_cache_validity & NFS_INO_REVAL_FORCED))
 		nfsi->cache_validity |= invalid;