spi: Add Faraday SPI controller support

The Faraday FTSSP010 is a multi-function controller
which supports I2S/SPI/SSP/AC97/SPDIF. However This
patch implements only the SPI mode.

NOTE:
The DMA and CS/Clock control logic has been altered
since hardware revision 1.19.0. So this patch
would first detects the revision id of the underlying
chip, and then switch to the corresponding software
control routines.

Signed-off-by: Kuo-Jung Su <dantesu@faraday-tech.com>
Signed-off-by: Jagannadha Sutradharudu Teki <jaganna@xilinx.com>
CC: Tom Rini <trini@ti.com>