bnxt_re: fix a crash in qp error event processing

bnxt_re: fix a crash in qp error event processing

In bnxt_qplib_process_qp_event(), for qp error events we look up the
qp-handle and pass it for further processing. But we don't check if the
handle is NULL. This could lead to a crash in the called functions when
that qp-handle is dereferenced, if the qp is destroyed in the meantime.
Fix this by checking for a valid qp-handle in that function.

Signed-off-by: Sriharsha Basavapatna <sriharsha.basavapatna@broadcom.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>