mtd: rename CONFIG_MTD -> CONFIG_DM_MTD

CONFIG_MTD must be reserved for the MTD core. Like any other
subsystem, prefix the symbol by DM when it comes to DM support.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Boris Brezillon <boris.brezillon@bootlin.com>
[trini: Add Kconfig files]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/gardena-smart-gateway-mt7688-ram_defconfig b/configs/gardena-smart-gateway-mt7688-ram_defconfig
index 9a149a5..6fea45e 100644
--- a/configs/gardena-smart-gateway-mt7688-ram_defconfig
+++ b/configs/gardena-smart-gateway-mt7688-ram_defconfig
@@ -53,7 +53,7 @@
 CONFIG_LED=y
 CONFIG_LED_BLINK=y
 CONFIG_LED_GPIO=y
-CONFIG_MTD=y
+CONFIG_DM_MTD=y
 CONFIG_MTD_SPI_NAND=y
 CONFIG_SPI_FLASH_GIGADEVICE=y
 CONFIG_SPI_FLASH_MACRONIX=y