spi: Pass pointer to spi_slave structure in spi_setup_slave

For spi_setup_slave, instead of making the platform driver return a
pointer to spi_slave structure, pass in a structure pointer that can be
filled in by the driver as required. This removes the need for platform
drivers to maintain a slave structure in data/CAR section.

TEST=Compiles successfully

Change-Id: Ia15a4f88ef4dcfdf616bb1c22261e7cb642a7573
Signed-off-by: Furquan Shaikh <furquan@chromium.org>
Reviewed-on: https://review.coreboot.org/17683
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
30 files changed