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>
diff --git a/arch/mips/configs/db1xxx_defconfig b/arch/mips/configs/db1xxx_defconfig
index c5a2c6f..bc9b6ae 100644
--- a/arch/mips/configs/db1xxx_defconfig
+++ b/arch/mips/configs/db1xxx_defconfig
@@ -95,7 +95,7 @@
 CONFIG_MTD_PHYSMAP=y
 CONFIG_MTD_M25P80=y
 CONFIG_MTD_SST25L=y
-CONFIG_MTD_NAND=y
+CONFIG_MTD_RAW_NAND=y
 CONFIG_MTD_NAND_ECC_SW_BCH=y
 CONFIG_MTD_NAND_AU1550=y
 CONFIG_MTD_NAND_PLATFORM=y