mtd: rawnand: Clarify Kconfig entry MTD_NAND

MTD_NAND is large and encloses much more than what the symbol is
actually used for: raw NAND. Clarify the symbol by naming it
MTD_RAW_NAND instead.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
82 files changed