ASoC: wm8994: Add support for MCLKn clock gating

ASoC: wm8994: Add support for MCLKn clock gating

As an intermediate step before covering the clocking subsystem
of the CODEC entirely by the clk API add handling of external CODEC's
master clocks in DAPM events when the AIFn clocks are sourced directly
from MCLKn; when FLLn are used we enable/disable respective MCLKn
before/after FLLn is enabled/disabled.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Acked-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Acked-by: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20190920130218.32690-5-s.nawrocki@samsung.com
Signed-off-by: Mark Brown <broonie@kernel.org>