sh: add support Renesas SH7723

Renesas SH7723 has 5 SCIF, SD, Camera, LCDC and other.
This patch supports CPU register's header file and SCIF serial driver.

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