ASoC: msm: qdsp6v2: Add get for App Type mixer control

Implement get function for App Type mixer control in
pcm and compress driver. Returns app type, ACDB ID,
and sample rate in use for FE ID.

Change-Id: I4972de893a638f2482c37796dd1718628526351d
Signed-off-by: Ben Romberger <bromberg@codeaurora.org>