net/enic: generate VXLAN src port if it is zero in template

net/enic: generate VXLAN src port if it is zero in template

When VXLAN source port in the template is zero, the adapter is
expected to generate a value based on the inner packet flow, when it
performs encapsulation. Flow Manager in the VIC adapter currently
lacks such ability. So, generate a random port when creating a flow if
the port is zero, to avoid transmitting packets with source port 0.

Fixes: ea7768b5bba8 ("net/enic: add flow implementation based on Flow Manager API")
Cc: stable@dpdk.org
Signed-off-by: Hyong Youb Kim <hyonkim@cisco.com>
Reviewed-by: John Daley <johndale@cisco.com>