msm: npu: Allow context switch after processing IPC message

Some of the IPC message requires long processing time. If there
are multiple messages in the queue, driver will finish processing
all of them before user process can be waken up. This change is to
force context switch each time after processing each IPC message
to allow user process to have a chance to run.

Change-Id: I3cdebe074834d85f89bb42fd872ae4733b6a8510
Signed-off-by: Jilai Wang <jilaiw@codeaurora.org>