msm: ipa: use single thread workqueue for ipa interrupts

Use create_singlethread_workqueue instead of create_workqueue to create
single worker thread and saving the order of execution of the tasks
in case of multi-processor system.

Change-Id: I0b7249dd66d45c1328785ef1688df3e97ef27f5d
Signed-off-by: Ravit Katzav <rkatzav@codeaurora.org>