ASoC: rockchip: i2s: set TDL and RDL to 16 samples

Set Transmit Data Level(TDL) and Receive Data Level(RDL) to 16 samples.
Without this setting, the TDL is default to be 0x00 (means 0 sample),
and the RDL is default to be 0x1f (means 32 samples).

Signed-off-by: Jianqun Xu <jay.xu@rock-chips.com>
Signed-off-by: Mark Brown <broonie@kernel.org>