ASoC: Cold start latency reduction

This patch parallelizes FE (front end) and BE (back end) when
playback/capture path is set up. FE's and BE's which can be
parallelized should be indicated in corresponding machine file.
All the operations can be started asynchronously provided the usecase
supports asynchronous operation.
Parallelizing reduces the startup latency as both FE and BE operations
run in parallel.

Change-Id: I17e7e1c3d406713cc728ec262cfe388f7251f7de
Signed-off-by: Walter Yang <yandongy@codeaurora.org>
Signed-off-by: Fred Oh <fred@codeaurora.org>
Signed-off-by: Banajit Goswami <bgoswami@codeaurora.org>
Signed-off-by: Meng Wang <mwang@codeaurora.org>