msm: ipa: Fix concurrency issue in A2 service

Bug fix for cuncurrency issue with A2 service and USB driver,
which creates a deadlock.
Added a workqueue to A2 service to solve this issue.

Change-Id: I39e3e2b81e4b4b218a6c56e01f3b643864aa85c7
Signed-off-by: Vladislav Mordohovich <vmordoho@codeaurora.org>