icnss: Handle multiple PD down notifications

During recovery, if another PD down notification received because
of crash then handle the case. If debug enabled then BUG_ON to
debug the second crash.

CRs-fixed: 1067873
Change-Id: I6e8e92ca0ee11830f933e198fea502c915d36e59
Signed-off-by: Prashanth Bhatta <bhattap@codeaurora.org>