MAINTAINERS: Remove my name from the MTD and NAND entries

I am less and less active on the MTD/NAND fronts, and I don't think
it will get any better in the future. Let's remove my name so that
people don't expect me to review/merge their patches.
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

MAINTAINERS

@@ -10008,7 +10008,6 @@ F:	mm/
 MEMORY TECHNOLOGY DEVICES (MTD)
 M:	David Woodhouse <dwmw2@infradead.org>
 M:	Brian Norris <computersforpeace@gmail.com>
-M:	Boris Brezillon <bbrezillon@kernel.org>
 M:	Marek Vasut <marek.vasut@gmail.com>
 M:	Richard Weinberger <richard@nod.at>
 M:	Vignesh Raghavendra <vigneshr@ti.com>
@@ -10623,7 +10622,6 @@ S:	Supported
 F:	drivers/net/ethernet/myricom/myri10ge/
 
 NAND FLASH SUBSYSTEM
-M:	Boris Brezillon <bbrezillon@kernel.org>
 M:	Miquel Raynal <miquel.raynal@bootlin.com>
 R:	Richard Weinberger <richard@nod.at>
 L:	linux-mtd@lists.infradead.org