Fix vxlan-gpe next protocol value
Fix vxlan-gpe next protocol value

vxlan4_gpe_rewrite and vxlan6_gpe_rewrite used the fixed value
VXLAN_GPE_PROTOCOL_IP4 for next protocol regardless of vxlan-gpe
port next protocol, this commit fixed it and used the value from
vxlan-gpe port.

Change-Id: I22ba25fbde1c0630960cbcfd196e14231fbf1af3
Signed-off-by: Yi Yang <1e26879e47df1049eb9cc7a5ee70fc952788cc72@intel.com>

vpp-dev/vpp,chrisy/vpp,vpp-dev/vpp,vpp-dev/vpp,milanlenco/vpp,FDio/vpp,FDio/vpp,milanlenco/vpp,FDio/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,chrisy/vpp,vpp-dev/vpp,milanlenco/vpp,GabrielGanne/vpp-flowtable,chrisy/vpp,GabrielGanne/vpp-flowtable,chrisy/vpp,GabrielGanne/vpp-flowtable,GabrielGanne/vpp-flowtable,milanlenco/vpp,chrisy/vpp,FDio/vpp,vpp-dev/vpp,chrisy/vpp,GabrielGanne/vpp-flowtable,FDio/vpp,vpp-dev/vpp,GabrielGanne/vpp-flowtable,milanlenco/vpp,vpp-dev/vpp,chrisy/vpp,milanlenco/vpp,FDio/vpp