ASoC: WM8994: Don't disable the AIF[1|2]CLK_ENA unconditionaly

Since we began using the late clock disable functionality, ensure that
we don't disable the clock if any of the ADC or DAC paths are still
enabled.  This happens when we have simultaneous playback and recording.

Signed-off-by: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: stable@kernel.org