nfsd4: shut down callback queue outside state lock

This reportedly causes a lockdep warning on nfsd shutdown.  That looks
like a false positive to me, but there's no reason why this needs the
state lock anyway.

Reported-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

fs/nfsd/nfs4state.c

@@ -4122,8 +4122,8 @@ nfs4_state_shutdown(void)
 	nfs4_lock_state();
 	nfs4_release_reclaim();
 	__nfs4_state_shutdown();
-	nfsd4_destroy_callback_queue();
 	nfs4_unlock_state();
+	nfsd4_destroy_callback_queue();
 }
 
 /*