Implement the generation of sdcard images with ext4 or
squashfs + f2fs overlay, but only enable the latter
automatically
Additionally, add mkf2fs and e2fsprogs to default packages
to manipulate ext4 and f2fs filesystems
Finally, disable the automatic generation of initramfs
and rootfs.tar.gz images, as they are no longer required
(they can still be selected in menuconfig)
Signed-off-by: Luis Araneda <luaraneda@gmail.com>