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: If7295c85dfb7daab8ad7d4d31b5b2b79f2ff1186
Signed-off-by: Da Hoon Pyun <dpyun@codeaurora.org>