sh: Add support T-SH7706LSR board

This patch supports T-SH7706LSR board.
This is constitution almost same as shmin (T-SH7706LAN).
Therefore, most functions work by a change of the setting of config.

http://web.kyoto-inet.or.jp/people/takagaki/T-SH7706/T-SH7706LSR.htm



Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>