Fix possible null pointer dereference
Fix possible null pointer dereference

Replace clib_warning with vlib_log_warn

Change-Id: I6d0b8d97048b75f4418609264af0c14e19fad79b
Signed-off-by: Juraj Sloboda <00a3e8e35b8aa66e4b3ee1ab4852a3d7bce0da23@cisco.com>

chrisy/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,vpp-dev/vpp,chrisy/vpp,chrisy/vpp,chrisy/vpp,chrisy/vpp,FDio/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,vpp-dev/vpp,vpp-dev/vpp,FDio/vpp,vpp-dev/vpp,FDio/vpp,chrisy/vpp,FDio/vpp,vpp-dev/vpp,vpp-dev/vpp,vpp-dev/vpp