MAINTAINERS: Add staging branch for HyperBus

Update HyperBus entry with branch used to stage patches under
mtd.git. Also, add mailing list and patchwork queue information.

Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Acked-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20200227051212.15496-1-vigneshr@ti.com

MAINTAINERS

@@ -7770,6 +7770,9 @@ F:	Documentation/ABI/testing/debugfs-hyperv
 
 HYPERBUS SUPPORT
 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
 S:	Supported
 F:	drivers/mtd/hyperbus/
 F:	include/linux/mtd/hyperbus.h