msm: gsi: enable wake irq

Allow GSI interrupt to wake up AP.
This change will prevent a data stall in case
AP is in power collapse and IPA has data available
to AP.

Change-Id: I6457d1e348cd8e7a9075396e02061843f0ac9abc
CRs-Fixed: 1012036
Acked-by: Ady Abraham <adya@qti.qualcomm.com>
Signed-off-by: Skylar Chang <chiaweic@codeaurora.org>