MAINTAINERS: Add the IRC channel to the MTD related subsystems

The #mtd channel (on OFTC servers) is being used to discuss MTD related
topics. Add it for better visibility to the HYPERBUS, NAND and SPI NOR
entries.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Acked-by: Miquel Raynal <miquel.raynal@bootlin.com>
Acked-by: Vignesh Raghavendra <vigneshr@ti.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

MAINTAINERS

@@ -7773,6 +7773,7 @@ M:	Vignesh Raghavendra <vigneshr@ti.com>
 L:	linux-mtd@lists.infradead.org
 Q:	http://patchwork.ozlabs.org/project/linux-mtd/list/
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git cfi/next
+C:	irc://irc.oftc.net/mtd
 S:	Supported
 F:	drivers/mtd/hyperbus/
 F:	include/linux/mtd/hyperbus.h
@@ -11455,6 +11456,7 @@ L:	linux-mtd@lists.infradead.org
 W:	http://www.linux-mtd.infradead.org/
 Q:	http://patchwork.ozlabs.org/project/linux-mtd/list/
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git nand/next
+C:	irc://irc.oftc.net/mtd
 S:	Maintained
 F:	drivers/mtd/nand/
 F:	include/linux/mtd/*nand*.h
@@ -15693,6 +15695,7 @@ L:	linux-mtd@lists.infradead.org
 W:	http://www.linux-mtd.infradead.org/
 Q:	http://patchwork.ozlabs.org/project/linux-mtd/list/
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git spi-nor/next
+C:	irc://irc.oftc.net/mtd
 S:	Maintained
 F:	drivers/mtd/spi-nor/
 F:	include/linux/mtd/spi-nor.h