MAINTAINERS: Add the IRC channel to the MTD entry

The #mtd channel (on OFTC servers) is being used to discuss MTD related
topics. Add it to the MTD entry.
Signed-off-by: Boris Brezillon <bbrezillon@kernel.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

MAINTAINERS

@@ -10537,6 +10537,7 @@ M:	Vignesh Raghavendra <vigneshr@ti.com>
 L:	linux-mtd@lists.infradead.org
 W:	http://www.linux-mtd.infradead.org/
 Q:	http://patchwork.ozlabs.org/project/linux-mtd/list/
+C:	irc://irc.oftc.net/mtd
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git mtd/fixes
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git mtd/next
 S:	Maintained