orignal GPIO chipslect is not standard because it don't take care to the
chipselect signal: BITBANG_CS_ACTIVE and BITBANG_CS_INACTIVE.
Signed-off-by: Qipan Li <Qipan.Li@csr.com>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Signed-off-by: Mark Brown <broonie@linaro.org>