ASoC: wcd: Add support for audio external clock driver on msmtitanium

Audio external clock 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: Iab978b326ade89b7ba8c558bb55403d9e5c0df0b
Signed-off-by: Laxminath Kasam <lkasam@codeaurora.org>