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/khadas-vim2_defconfig b/configs/khadas-vim2_defconfig
index cc9935d..0c07f5c 100644
--- a/configs/khadas-vim2_defconfig
+++ b/configs/khadas-vim2_defconfig
@@ -29,7 +29,7 @@
 CONFIG_DM_GPIO=y
 CONFIG_DM_MMC=y
 CONFIG_MMC_MESON_GX=y
-CONFIG_MTD=y
+CONFIG_DM_MTD=y
 CONFIG_PHY_REALTEK=y
 CONFIG_DM_ETH=y
 CONFIG_ETH_DESIGNWARE=y