MAINTAINERS: nilfs2: update email address

Change my email since lab.ntt.co.jp email domain has been deprecated due
to company policy.

Link: http://lkml.kernel.org/r/1562495153-8166-1-git-send-email-konishi.ryusuke@gmail.com
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

MAINTAINERS

@@ -11215,7 +11215,7 @@ F:	include/uapi/linux/nfs*
 F:	include/uapi/linux/sunrpc/
 
 NILFS2 FILESYSTEM
-M:	Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
+M:	Ryusuke Konishi <konishi.ryusuke@gmail.com>
 L:	linux-nilfs@vger.kernel.org
 W:	https://nilfs.sourceforge.io/
 W:	https://nilfs.osdn.jp/