cnss2: Handle event processing after shutdown

WLFW qmi server arrive event posted and comes server exit event
as there is a shutdown triggered due to reboot. Hence do not process
WLFW qmi server arrive event.

Change-Id: Ic5d75cc245f6b4caf7987031bfe117236e93f54e
Signed-off-by: Nirav Shah <quic_nnshah@quicinc.com>