meta-dream: Remove UBI support from dm500hd defconfig

The CONFIG_UBIFS_FS is disabled.
Config regenerated via command "MACHINE=dm500hd bitbake -c menuconfig virtual/kernel"

This is the second attempt to make kernel smaller than some "magic" number
so it won't bump into bootloader bugs.

Signed-off-by: Mike Looijmans <milo-software@users.sourceforge.net>
Merge branch 'master' of git://git.code.sf.net/p/openpli/openpli-oe-core