NFS: Only define some function when v4.1 is enabled

Now that the nfs4_cb_match_client() function is static, gcc notices that
it is only used when CONFIG_NFS_V4_1 is enabled.

Signed-off-by: Bryan Schumaker <[e-mail]>
Signed-off-by: Trond Myklebust <[e-mail]>

fs/nfs/client.c

···
 		(sin1->sin_port == sin2->sin_port);
 }
 
+#if defined(CONFIG_NFS_V4_1)
 /*
  * Test if two socket addresses represent the same actual socket,
  * by comparing (only) relevant fields, excluding the port number.
···
 	}
 	return 0;
 }
+#endif /* CONFIG_NFS_V4_1 */
 
 /*
  * Test if two socket addresses represent the same actual socket,
···
 	return 0;
 }
 
+#if defined(CONFIG_NFS_V4_1)
 /* Common match routine for v4.0 and v4.1 callback services */
 static bool nfs4_cb_match_client(const struct sockaddr *addr,
 		struct nfs_client *clp, u32 minorversion)
···
 
 	return true;
 }
+#endif /* CONFIG_NFS_V4_1 */
 
 /*
  * Find an nfs_client on the list that matches the initialisation data