ASoC: refactor wcd9320, wcd9306 objects

Common objects for wcd9320 and wcd9306 codecs are being
compiled separately for those codecs. This makes the
compilation of both codecs in the same image impossible.
Msmsamarium will require both codecs to be compiled.
This change refactors the common objects to
enable wcd9320 and wcd9306 to be built in the same image.

Change-Id: I682adce18bad93c1d37042ea68d98c39e3f1c39d
Signed-off-by: Damir Didjusto <damird@codeaurora.org>