wip: Set the correct mclk clock rate

For some reason, rockchip_i2s_tdm_hw_params is called with 44100 when the userspace specifies 22050 Hz.
On some devices, it works, on others, it doesn't.

Luckily, before 9e2ab4b1,
rockchip_i2s_tdm_set_sysclk was used to configure the actual clock rate to be used.
This commit reuses that as it is called with the actual 22050 Hz rate.

[to be improved and better understood]