NFSD: Don't start lockd when only NFSv4 is running

When starting without nfsv2 and nfsv3, nfsd does not need to start
lockd (and certainly doesn't need to fail because lockd failed to
register with the portmapper).

Reported-by: Gareth Williams <gareth@garethwilliams.me.uk>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h
index 849a7c3..d32b3aa 100644
--- a/fs/nfsd/netns.h
+++ b/fs/nfsd/netns.h
@@ -95,6 +95,7 @@
 	time_t nfsd4_grace;
 
 	bool nfsd_net_up;
+	bool lockd_up;
 
 	/*
 	 * Time of server startup