mtd: rename CONFIG_MTD_DEVICE -> CONFIG_MTD

Like in Linux, just use CONFIG_MTD to compile the MTD stack.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Boris Brezillon <boris.brezillon@bootlin.com>
diff --git a/configs/x530_defconfig b/configs/x530_defconfig
index 7441e15..3592e6b 100644
--- a/configs/x530_defconfig
+++ b/configs/x530_defconfig
@@ -56,6 +56,7 @@
 CONFIG_I2C_MUX=y
 CONFIG_I2C_MUX_PCA954x=y
 # CONFIG_MMC is not set
+CONFIG_MTD=y
 CONFIG_MTD_RAW_NAND=y
 CONFIG_SYS_NAND_USE_FLASH_BBT=y
 CONFIG_NAND_PXA3XX=y