arm: rmobile: Add SH QSPI base register address

This adds base register address of SH QSPI.
Currently, SH QSPI is used only from R8A7790 and R8A7791.

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