spi: sun6i: Fix define for SUN6I_TFR_CTL_CS_MASK

Current code in sun6i_spi_set_cs() actually clears CPHA and CPOL bits which is
obvious wrong. The define for SUN6I_TFR_CTL_CS_MASK is wrong. Fix it.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Mark Brown <broonie@linaro.org>