sh: L-BOX RE2 support.

This adds support for the L-BOX RE2 router.

	http://www.nttcom.co.jp/l-box/

L-BOX RE2 is a SH7751R-based router. It has CF, Cardbus, serial,
and LAN x2. This is one of the very few SH boards that a general
person can obtain now.

The L-BOX shipped with a 2.4.28 kernel, this is a rewritten patch
adding it to current git.

Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>