spi: Add SPI mode enums

With ACPI we need to describe the settings of the SPI bus. Add enums to
handle this.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Wolfgang Wallner <wolfgang.wallner@br-automation.com>
1 file changed