For ac97, the registers have to be setup earlier than for other ssi
modes because there is some communication with the external device
before streaming. So this patch introduces a fsl_ssi_setup function to
setup the registers for different ssi operation modes seperately.
This patch was tested with imx27-pca100.
Signed-off-by: Markus Pargmann <mpa@pengutronix.de> Tested-by: Shawn Guo <shawn.guo@linaro.org> Signed-off-by: Mark Brown <broonie@linaro.org>