ASoC: wcd9310: Fix audio playback and capture

Fix the read and write functions which are passing the wrong
parameter to the wcd9xxx helper function.
Fix the virual port amix command for audio capture.
Use a separate structure for each amix command.

Change-Id: I64a7c98d18d99fec515011bed475c78fc8c6d55a
Signed-off-by: Damir Didjusto <damird@codeaurora.org>