poky-tiny: ext2 isn't enabled in the kernel so don't mention/build it

The kernel config specifically excludes ext2 support for size reasons
so update the distro config to match.

(From meta-yocto rev: 12440cd591de0f73426c310cc7affab9e2ef5fe0)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta-yocto/conf/distro/poky-tiny.conf

@@ -105,11 +105,11 @@ VIRTUAL-RUNTIME_keymaps = ""
 # packagegroup-core-base to select modutils-initscripts or not.  Similar with "net" and
 # netbase.
 
-# By default we only support ext2 and initramfs. We don't build live as that
+# By default we only support initramfs. We don't build live as that
 # pulls in a lot of dependencies for the live image and the installer, like
 # udev, grub, etc.  These pull in gettext, which fails to build with wide
 # character support.
-IMAGE_FSTYPES = "ext2 cpio.gz"
+IMAGE_FSTYPES = "cpio.gz"
 
 # Drop v86d from qemu dependency list (we support serial)
 # Drop grub from meta-intel BSPs