MAINTAINERS: Add a bugzilla link for NFSD

I recently found out about B: for noting where subsystem bugs can be
filed. I do pay attention to bugzilla.kernel.org. The Linux NFS
community has decided to steer kernel NFS issues to the kernel.org
bugzilla instead of bugzilla.linux-nfs.org.

Remove the W: entry; the sourceforge information is stale and
unmaintained.

Cc: Thorsten Leemhuis <linux@leemhuis.info>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

MAINTAINERS

@@ -11979,7 +11979,7 @@ R:	Dai Ngo <Dai.Ngo@oracle.com>
 R:	Tom Talpey <tom@talpey.com>
 L:	linux-nfs@vger.kernel.org
 S:	Supported
-W:	http://nfs.sourceforge.net/
+B:	https://bugzilla.kernel.org
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux.git
 F:	Documentation/filesystems/nfs/
 F:	fs/lockd/