msm: gsi: wait for interrupts for commands

When sending a command to gsi, an interrupt is expected.
This change is waiting for this interrupt until timeout
has expired.

Change-Id: I876c4386aa34d90a1449aed308c99f93d61837d6
Acked-by: Ady Abraham <adya@qti.qualcomm.com>
Signed-off-by: Skylar Chang <chiaweic@codeaurora.org>