spi: Add support SH Quad SPI driver

This patch adds a driver for Renesas SoC's Quad SPI bus.
This supports with 8 bits per transfer to use with SPI flash.

Signed-off-by: Kouei Abe <kouei.abe.cp@renesas.com>
Signed-off-by: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com>
Signed-off-by: Jagannadha Sutradharudu Teki <jaganna@xilinx.com>