busybox: disable MTD utils in default configuration

The MTD utils require MTD headers in the toolchain, and in several
external toolchains, they are not present. In order to make the build
work by default, let's disable the MTD Busybox applets in our default
configuration.

Fixes bug #1669

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/busybox/busybox-1.16.x.config

@@ -604,10 +604,10 @@ CONFIG_DEVMEM=y
 CONFIG_EJECT=y
 # CONFIG_FEATURE_EJECT_SCSI is not set
 # CONFIG_FBSPLASH is not set
-CONFIG_FLASHCP=y
-CONFIG_FLASH_LOCK=y
-CONFIG_FLASH_UNLOCK=y
-CONFIG_FLASH_ERASEALL=y
+# CONFIG_FLASHCP is not set
+# CONFIG_FLASH_LOCK is not set
+# CONFIG_FLASH_UNLOCK is not set
+# CONFIG_FLASH_ERASEALL is not set
 # CONFIG_IONICE is not set
 # CONFIG_INOTIFYD is not set
 CONFIG_LAST=y