spi: kirkwood_spi: implement workaround for FE-9144572

spi: kirkwood_spi: implement workaround for FE-9144572

Erratum NO. FE-9144572: The device SPI interface supports frequencies of
up to 50 MHz.  However, due to this erratum, when the device core clock
is 250 MHz and the SPI interfaces is configured for 50MHz SPI clock and
CPOL=CPHA=1 there might occur data corruption on reads from the SPI
device.

Implement the workaround by setting the TMISO_SAMPLE value to 0x2
in the timing1 register.

Signed-off-by: Chris Packham <judge.packham@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>
Reviewed-by: Jagan Teki <jagan@openedev.com>