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/brppt1_nand_defconfig b/configs/brppt1_nand_defconfig
index 5ffc51a..d62b85d 100644
--- a/configs/brppt1_nand_defconfig
+++ b/configs/brppt1_nand_defconfig
@@ -99,3 +99,4 @@
 # CONFIG_OF_LIBFDT_OVERLAY is not set
 # CONFIG_EFI_LOADER is not set
 CONFIG_MTD=y
+CONFIG_MTD_RAW_NAND=y