mtd: ensure MTD is compiled when CMD_MTDPARTS is selected

MTD support must be enabled when using mtdparts. Indeed, functions
like get_mtd_info(), get_mtd_device() and put_mtd_device() are in
drivers/mtd/mtd_uboot.c and are built only with CONFIG_MTD.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Boris Brezillon <boris.brezillon@bootlin.com>
diff --git a/configs/T2080RDB_NAND_defconfig b/configs/T2080RDB_NAND_defconfig
index b9348b4..530b92a 100644
--- a/configs/T2080RDB_NAND_defconfig
+++ b/configs/T2080RDB_NAND_defconfig
@@ -78,3 +78,4 @@
 CONFIG_USB_STORAGE=y
 CONFIG_DM_MMC=y
 CONFIG_MTD=y
+CONFIG_MTD_RAW_NAND=y