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/xpress_spl_defconfig b/configs/xpress_spl_defconfig
index a7bb6e9..6d4d7c4 100644
--- a/configs/xpress_spl_defconfig
+++ b/configs/xpress_spl_defconfig
@@ -41,6 +41,7 @@
 CONFIG_SYS_RELOC_GD_ENV_ADDR=y
 CONFIG_SUPPORT_EMMC_BOOT=y
 CONFIG_FSL_USDHC=y
+CONFIG_MTD=y
 CONFIG_PHYLIB=y
 CONFIG_MII=y
 CONFIG_USB=y