soc: mimxrt595s/cm33, mimxrt685s/cm33: Add clock config for audio

Add clock config for Flexcomm peripherals functioning as I2S interfaces.
Add MCLK clock config for the WM8904 codec located on the mimxrt595_evk
and mimxrt685_evk boards.

Signed-off-by: Hake Huang <hake.huang@oss.nxp.com>
Signed-off-by: Yves Vandervennet <yves.vandervennet@nxp.com>
Signed-off-by: Vit Stanicek <vit.stanicek@nxp.com>