nfsd4: setclientid_confirm callback-change fixes

This setclientid_confirm case should allow the client to change
callbacks, but it currently has a dummy implementation that just turns
off callbacks completely.  That dummy implementation isn't completely
correct either, though:

	- There's no need to remove any client recovery directory in
	  this case.
	- New clientid confirm verifiers should be generated (and
	  returned) in setclientid; there's no need to generate a new
	  one here.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

fs/nfsd/nfs4state.c

@@ -1688,8 +1688,6 @@ nfsd4_setclientid_confirm(struct svc_rqst *rqstp,
 			/* XXX: We just turn off callbacks until we can handle
 			  * change request correctly. */
 			atomic_set(&conf->cl_callback.cb_set, 0);
-			gen_confirm(conf);
-			nfsd4_remove_clid_dir(unconf);
 			expire_client(unconf);
 			status = nfs_ok;