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/ls2088ardb_qspi_defconfig b/configs/ls2088ardb_qspi_defconfig
index ae77006..86cda4f 100644
--- a/configs/ls2088ardb_qspi_defconfig
+++ b/configs/ls2088ardb_qspi_defconfig
@@ -38,6 +38,7 @@
 CONFIG_DM_MMC=y
 CONFIG_FSL_ESDHC=y
 CONFIG_DM_SPI_FLASH=y
+CONFIG_MTD=y
 # CONFIG_SPI_FLASH_BAR is not set
 CONFIG_SPI_FLASH_SPANSION=y
 # CONFIG_SPI_FLASH_USE_4K_SECTORS is not set