ASoC: fsl_sai: Implement set_bclk_ratio

This is to allow machine drivers to set a certain bitclk rate
which might not be exactly rate * frame size.

Cc: NXP Linux Team <linux-imx@nxp.com>
Signed-off-by: Viorel Suman <viorel.suman@nxp.com>
Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
Acked-by: Nicolin Chen <nicoleotsuka@gmail.com>
Link: https://lore.kernel.org/r/20190830215910.31590-1-daniel.baluta@nxp.com


Signed-off-by: Mark Brown <broonie@kernel.org>