spi: add ti-ssp spi master driver

This patch adds an SPI master implementation that operates on top of an
underlying TI-SSP port.

Acked-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Cyril Chemparathy <cyril@ti.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>

diff --cc drivers/spi/Kconfig
Simple merge

diff --cc drivers/spi/Makefile
Simple merge

diff --cc drivers/spi/ti-ssp-spi.c
Simple merge

diff --cc include/linux/mfd/ti_ssp.h
Simple merge