ASoC: wcd: Add support for audio external clock driver

Add support for new audio external clock driver in 8952.
This driver registers to kernel clock framework and
provides clock ops to enable the external (reference) clock
to audio codec hardware. This clock needs to be enabled
for any audio use-cases to run.

Change-Id: I67cd78b801e8354cd7217f94979cf939023fcbcf
Signed-off-by: Aravind Kumar <akumark@codeaurora.org>
Signed-off-by: Venkata Narendra Kumar Gutta <vgutta@codeaurora.org>