serial: sh-sci: Add support SCIF of SH7723

SH7723 has two types of SCIF (SCIF and SCIFA).
The current sh-sci driver supports only SCIFA, and calculation methods of SCBRR
are different.
This patch support this methods.

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