Patch merged into coreboot/master: spi: Clean up SPI driver interface

the following patch was just integrated into master:
commit b5d41cb063a54d2a90e0480ede18d3b9c1ae8474
Author: Furquan Shaikh 
Date:   Thu Dec 1 07:25:31 2016 -0800

spi: Clean up SPI driver interface

1. Add new structure spi_ctrlr_buses that allows platform to define a
    mapping from SPI controller to buses managed by the controller.
    2. Provide weak implementations of spi_init and spi_setup_slave that
    will be used by platforms using the new interface.

BUG=chrome-os-partner:59832
    BRANCH=None
    TEST=Compiles successfully

Change-Id: Ia6f47941b786299f4d823895898ffb1b36e02f73
    Signed-off-by: Furquan Shaikh 
    Reviewed-on: https://review.coreboot.org/17561
    Tested-by: build bot (Jenkins)
    Reviewed-by: Aaron Durbin

See https://review.coreboot.org/17561 for details.

-gerrit