classify: crash on classify filter pcap del command
classify: crash on classify filter pcap del command

If classify pcap filter was never configured, typing the delete
command causes a crash. The reason is
cm->classify_table_index_by_sw_if_index not yet allocated.

The fix is to add a check before we access the vector.

Type: fix
Fixes: gerrit 28475

Signed-off-by: Steven Luong <a748ea44ad7b179c2313a856d44e1e4eb39869bb@cisco.com>
Change-Id: Ia33bd91fa82d8ffc4490d4069155980a6e233268

FDio/vpp,chrisy/vpp,chrisy/vpp,chrisy/vpp,chrisy/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,FDio/vpp,FDio/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,chrisy/vpp,chrisy/vpp,FDio/vpp