ASoC: msm: Support for configuring buffer size in multichannel PCM TX

There is a usecase to capture PCM from HDMI input through ADSP using
MI2S TX interface and play or route the same to the desired output
device. To support this more buffering is required. Add configuring
buffer size in multi channel PCM TX driver to support the usecase.

Change-Id: Icefa803b02cd5edac0f67fe2186b44030c38c8b9
Signed-off-by: Subhash Chandra Bose Naripeddy <snariped@codeaurora.org>