ADC and DAC can be clocked from separate or same sources CLK1 and CLK2.
By default, ADC is clocked from CLK1, and DAC - from CLK2.

This commits allows sound cards to selest a proper clock source during
`hw_params()` via `snd_soc_dai_set_sysclk()`. It makes possible to have a
single clock source for both ADC and DAC.
Signed-off-by: Kirill Marinushkin <kmarinushkin@birdec.tech>
Signed-off-by: Mark Brown <broonie@kernel.org>