MAINTAINERS: Move all MTD related branches to a single repo

Historically, branches targeting the next release (and pulled in
linux-next) have been pushed on the l2-mtd repo and fixes branches on
the linux-mtd one. Now that all MTD maintainers have RW permissions on
linux-mtd tree, there's no good reason to have two different trees.
Move all -next branches to linux-mtd.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Marek Vasut <marek.vasut@gmail.com>
Cc: Cyrille Pitchen <cyrille.pitchen@wedev4u.fr>
Cc: Richard Weinberger <richard@nod.at>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Brian Norris <computersforpeace@gmail.com>
Acked-by: Richard Weinberger <richard@nod.at>
Acked-by: Cyrille Pitchen <cyrille.pitchen@wedev4u.fr>

MAINTAINERS

@@ -8956,7 +8956,7 @@ 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.infradead.org/linux-mtd.git master
-T:	git git://git.infradead.org/l2-mtd.git master
+T:	git git://git.infradead.org/linux-mtd.git mtd/next
 S:	Maintained
 F:	Documentation/devicetree/bindings/mtd/
 F:	drivers/mtd/
@@ -9344,7 +9344,7 @@ 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.infradead.org/linux-mtd.git nand/fixes
-T:	git git://git.infradead.org/l2-mtd.git nand/next
+T:	git git://git.infradead.org/linux-mtd.git nand/next
 S:	Maintained
 F:	drivers/mtd/nand/
 F:	include/linux/mtd/*nand*.h
@@ -12761,7 +12761,7 @@ 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.infradead.org/linux-mtd.git spi-nor/fixes
-T:	git git://git.infradead.org/l2-mtd.git spi-nor/next
+T:	git git://git.infradead.org/linux-mtd.git spi-nor/next
 S:	Maintained
 F:	drivers/mtd/spi-nor/
 F:	include/linux/mtd/spi-nor.h