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 opeations
run in parallel.

Change-Id: I9eeaf500b6d90d4def0adc1bdd6c219e49f676c7
Signed-off-by: Anish Kumar <kanish@codeaurora.org>