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/mx7ulp_evk_plugin_defconfig b/configs/mx7ulp_evk_plugin_defconfig
index 0b07962..1c37d6b 100644
--- a/configs/mx7ulp_evk_plugin_defconfig
+++ b/configs/mx7ulp_evk_plugin_defconfig
@@ -27,6 +27,7 @@
 CONFIG_DM_MMC=y
 CONFIG_SUPPORT_EMMC_BOOT=y
 CONFIG_FSL_USDHC=y
+CONFIG_MTD=y
 CONFIG_PINCTRL=y
 CONFIG_PINCTRL_IMX7ULP=y
 CONFIG_DM_REGULATOR=y