msm: ipa: clear before processing

Clear the interrupts before processing
to avoid race conditions on same type
of interrupts

Change-Id: I566427cac234fb5dc85f0fb218ad06fd7e057edb
Acked-by: Sunil Paidimarri <hisunil@qti.qualcomm.com>
Signed-off-by: Skylar Chang <chiaweic@codeaurora.org>