dsp: afe: add support for VA macro codec DMA interface

VA macro on Kona has three TX codec DMA interface. The
current AFE driver only supports two codec DMA interface.
Add support to enable the third one in AFE driver.

Change-Id: Ie0f6241ef37bc03ad9adb1c4fe82f82468caec25
Signed-off-by: Xiaoyu Ye <benyxy@codeaurora.org>