spi: ich: Configure SPI BIOS parameters for Linux upon U-Boot exit

This patch adds a remove function to the Intel ICH SPI driver, that will
be called upon U-Boot exit, directly before the OS (Linux) is started.
This function takes care of configuring the BIOS registers in the SPI
controller (similar to what a "standard" BIOS or coreboot does), so that
the Linux MTD device driver is able to correctly read/write to the SPI
NOR chip. Without this, the chip is not detected at all.

Signed-off-by: Stefan Roese <sr@denx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Cc: Bin Meng <bmeng.cn@gmail.com>
Cc: Jagan Teki <jteki@openedev.com>