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/drivers/mtd/Makefile b/drivers/mtd/Makefile
index 88e5711..bd4f533 100644
--- a/drivers/mtd/Makefile
+++ b/drivers/mtd/Makefile
@@ -3,7 +3,7 @@
 # (C) Copyright 2000-2007
 # Wolfgang Denk, DENX Software Engineering, wd@denx.de.
 
-ifneq (,$(findstring y,$(CONFIG_MTD_DEVICE)$(CONFIG_CMD_NAND)$(CONFIG_CMD_ONENAND)$(CONFIG_CMD_SF)$(CONFIG_CMD_MTD)))
+ifneq (,$(findstring y,$(CONFIG_MTD)$(CONFIG_CMD_NAND)$(CONFIG_CMD_ONENAND)$(CONFIG_CMD_SF)$(CONFIG_CMD_MTD)))
 obj-y += mtdcore.o mtd_uboot.o
 endif
 obj-$(CONFIG_DM_MTD) += mtd-uclass.o