Fix GTP-U Coverity issues
Fix GTP-U Coverity issues

Change-Id: I982e0dfb96c371672aa636aa7e40f06a84e2bb69
Signed-off-by: Hongjun Ni <e6547d24d7149371d2bb4b8f7cc3ef66745c46d6@intel.com>

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