ASoC: sun4i-i2s: Fix setting of FIFO modes

ASoC: sun4i-i2s: Fix setting of FIFO modes

Because SUN4I_I2S_FIFO_CTRL_REG is volatile, writes done while the
regmap is cache-only are ignored. To work around this, move the
configuration to a callback that runs while the ASoC core has a
runtime PM reference to the device.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Reviewed-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Clément Péron <peron.clem@gmail.com>
Link: https://lore.kernel.org/r/20201030144648.397824-9-peron.clem@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>