NFSv4: Ensure that nfs4_alloc_client cleans up on error.

Any pointer that was allocated through nfs_alloc_client() needs to be
freed via a call to nfs_free_client().

Reported-by: Stanislav Kinsbursky <[e-mail]>
Signed-off-by: Trond Myklebust <[e-mail]>

fs/nfs/nfs4client.c

···
 	return clp;
 
 error:
-	kfree(clp);
+	nfs_free_client(clp);
 	return ERR_PTR(err);
 }