ASoC: sun4i-i2s: Pass the channels number as an argument

The channels number have been hardcoded to 2 so far, while the controller
supports more than that.

Remove the instance where it has been hardcoded to compute the BCLK
divider, and pass it through as an argument to ease further support of more
channels.

Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://lore.kernel.org/r/48887cf7abfaab6597db233b24d7a088a913e48a.1566242458.git-series.maxime.ripard@bootlin.com


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