Add SPI friendly clock rates to the spi freq table.
Today it's not possible to use SPI at lower than 960Khz.
This patch adds 100/250/500/1000 kHz configs to the table.
Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>