arm: koelsch: Add support QSPI device and enable boot from SPI flash

This supports SH-QSPI device on koelsch board, and enable booting from
SPI flash.

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