msm: pci: Release spinlock before notifying client

Release spinlock before notifying client driver and acquire
spinlock once done because once host notifies client driver with
an event, client can schedule an recovery in same context before
returning and expects an new event which could cause an race
condition if spinlock is acquired.
Also use list_for_each_entry_safe() while travesing the list of
registered clients for notification.

Change-Id: I6ae55032acdb1a5b14f473eadacb7a009a8df753
Signed-off-by: Vivek Pernamitta <vpernami@codeaurora.org>