configs: pandaboard: correct genimage dependencies

The genimage configuration creates a vfat filesystem, so ensure we have
dosfstools / mtools built for the host.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

configs/pandaboard_defconfig

@@ -26,3 +26,4 @@ BR2_TARGET_UBOOT_SPL=y
 BR2_TARGET_UBOOT_SPL_NAME="MLO"
 BR2_PACKAGE_HOST_DOSFSTOOLS=y
 BR2_PACKAGE_HOST_GENIMAGE=y
+BR2_PACKAGE_HOST_MTOOLS=y