mtd: nand: Drop useless 'depends on' in Kconfig

Both OneNAND and raw NAND bits can't be compiled if MTD is disabled
because of the if/endif logic in drivers/mtd/Kconfig. There is no need
for an extra "depends on MTD" in their respective Kconfig files.
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Link: https://lore.kernel.org/linux-mtd/20200529002517.3546-12-miquel.raynal@bootlin.com

drivers/mtd/nand/onenand/Kconfig

 # SPDX-License-Identifier: GPL-2.0-only
 menuconfig MTD_ONENAND
 	tristate "OneNAND Device Support"
-	depends on MTD
 	depends on HAS_IOMEM
 	help
 	  This enables support for accessing all type of OneNAND flash

drivers/mtd/nand/raw/Kconfig

@@ -12,7 +12,6 @@ config MTD_NAND_ECC_SW_HAMMING_SMC
 
 menuconfig MTD_RAW_NAND
 	tristate "Raw/Parallel NAND Device Support"
-	depends on MTD
 	select MTD_NAND_CORE
 	select MTD_NAND_ECC_SW_HAMMING
 	help