mtd: ensure MTD is compiled when there is a SPI NOR flash using MTD

MTD must be enabled when there is a SPI NOR flash using the
SPI_FLASH_MTD config entry.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Boris Brezillon <boris.brezillon@bootlin.com>
diff --git a/configs/ls1012ardb_tfa_defconfig b/configs/ls1012ardb_tfa_defconfig
index 4c57430..0991f19 100644
--- a/configs/ls1012ardb_tfa_defconfig
+++ b/configs/ls1012ardb_tfa_defconfig
@@ -40,6 +40,7 @@
 CONFIG_MMC_HS200_SUPPORT=y
 CONFIG_FSL_ESDHC=y
 CONFIG_DM_SPI_FLASH=y
+CONFIG_MTD=y
 # CONFIG_SPI_FLASH_BAR is not set
 # CONFIG_SPI_FLASH_USE_4K_SECTORS is not set
 CONFIG_FSL_PFE=y