usb: phy-msm-usb: Add check to ignore duplicate PMIC events

USB gets notification from PMIC for vbus connect and disconnect events.
Based on the event notification type, USB schedule state machine where
it executes operations needed for usb connnect/disconnect processing.
If duplicate connect/disconnect notifications (spurious events) comes
from PMIC, then in current code USB schedule state machine without
checking previous notification type from PMIC.

In current scenario, USB is getting duplicate disconnect events from
PMIC (2nd disconnect is spurious) followed by connect event. Due to these
sequence of events PM counter in the otg state machine is decremented to
zero which calls otg runtime suspend leading to unclocked access while
processing USB connect.

Fix the issue by adding proper check to ignore duplicate PMIC connect
and disconnect notifications.

CRs-Fixed: 664203
Change-Id: I59dac5bf42bf24e9670b6fbdb8a4d736b195d88f
Signed-off-by: Saket Saurabh <ssaurabh@codeaurora.org>