ARM: davinci_all_defconfig: enable mtdtests

mtdtests module has some useful tests to verify that
mtd drivers like davinci_nand are working correctly.

Enable it in davinci_all_defconfig to make testing and
debug easier.
Signed-off-by: Sekhar Nori <nsekhar@ti.com>

arch/arm/configs/davinci_all_defconfig

@@ -58,6 +58,7 @@ CONFIG_DEVTMPFS_MOUNT=y
 # CONFIG_FW_LOADER is not set
 CONFIG_DA8XX_MSTPRI=y
 CONFIG_MTD=m
+CONFIG_MTD_TESTS=m
 CONFIG_MTD_BLOCK=m
 CONFIG_MTD_CFI=m
 CONFIG_MTD_CFI_INTELEXT=m