msm: gsi: fix to client notify on poll mode

When processing an IEOB interrupt, do not process the pending
events in case the channel is in polling mode.

Change-Id: I9b9fbc71ae33fe1bfef837580f9f8e9aa875160d
CRs-Fixed: 1112064
Acked-by: Ady Abraham <adya@qti.qualcomm.com>
Signed-off-by: Skylar Chang <chiaweic@codeaurora.org>