board/minnowboard-max: Rework to generate SD card image

Let's rework the board and config files to use genimage
to generate the SD card image directly.

[Peter: add host-mtools for genimage vfat handling]
Signed-off-by: Ezequiel García <ezequiel@vanguardiasur.com.ar>
Reviewed-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
diff --git a/configs/minnowboard_max_defconfig b/configs/minnowboard_max_defconfig
index 98996db..05df987 100644
--- a/configs/minnowboard_max_defconfig
+++ b/configs/minnowboard_max_defconfig
@@ -5,9 +5,13 @@
 # Misc
 BR2_TARGET_GENERIC_GETTY_PORT="ttyS0"
 BR2_ROOTFS_POST_BUILD_SCRIPT="board/minnowboard-max/post-build.sh"
+BR2_ROOTFS_POST_IMAGE_SCRIPT="board/minnowboard-max/post-image.sh"
 
 # Linux headers same as kernel, a 4.4 series
 BR2_PACKAGE_HOST_LINUX_HEADERS_CUSTOM_4_4=y
+BR2_PACKAGE_HOST_DOSFSTOOLS=y
+BR2_PACKAGE_HOST_GENIMAGE=y
+BR2_PACKAGE_HOST_MTOOLS=y
 
 # Needed for ethernet
 BR2_PACKAGE_LINUX_FIRMWARE=y
@@ -23,3 +27,8 @@
 # Bootloader
 BR2_TARGET_GRUB2=y
 BR2_TARGET_GRUB2_X86_64_EFI=y
+
+# Filesystem image
+BR2_TARGET_ROOTFS_EXT2=y
+BR2_TARGET_ROOTFS_EXT2_4=y
+# BR2_TARGET_ROOTFS_TAR is not set