msm: audio: qdsp6v2: Update correct stream parameters for tunnel mode

Add a new member for sample rate in the aac_config structure,
driver to use this value to update sample rate not the sample rate
set in pcm_config structure for tunnelmode.

Change-Id: I2cd38478673c90bb94d12124f89ab03382ca70e9
Signed-off-by: Sidipotu Ashok <sashok@codeaurora.org>