ARM: rmobile: Enable multi-DTB fit LZO compression

Enable LZO compression of the multi-DTB fitImages, since the U-Boot
with multiple DTs enabled is becoming quite large and the DTs can
be well compressed. The LZO compression saves almost 200 kiB on the
Salvator-X(S) and ULCB targets.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>