drivers/mtd : move mtd drivers to drivers/mtd

Makefile

drivers/mtd/Makefile

drivers/mtd/at45.c

drivers/mtd/cfi_flash.c

drivers/mtd/dataflash.c

drivers/mtd/mw_eeprom.c

drivers/mtd/nand/Makefile

drivers/mtd/nand/diskonchip.c

drivers/mtd/nand/nand.c

drivers/mtd/nand/nand_base.c

drivers/mtd/nand/nand_bbt.c

drivers/mtd/nand/nand_ecc.c

drivers/mtd/nand/nand_ids.c

drivers/mtd/nand/nand_util.c

drivers/mtd/nand_legacy/Makefile

drivers/mtd/nand_legacy/nand_legacy.c

drivers/mtd/onenand/Makefile

drivers/mtd/onenand/onenand_base.c

drivers/mtd/onenand/onenand_bbt.c

nand_spl/board/amcc/acadia/Makefile