ASoC: sun4i-i2s: Fix RX slot number of SUN8I

I2S's RX slot number of SUN8I should be shifted 4 bit to left.

Fixes: 7d299381

 ("ASoC: sun4i-i2s: Add support for H3")
Signed-off-by: Yong Deng <yong.deng@magewell.com>
Reviewed-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org