arm: rmobile: koelsch: Migrate serial driver to drivers model

This adds drivers model support of serial port to Koelsch board,
and migrate serial port to drivers model.

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