i40e: Call geneve_get_rx_port to get the existing Geneve ports

This patch adds a call to geneve_get_rx_port in i40e so that when it
comes up it can learn about the existing geneve tunnels.

Signed-off-by: Anjali Singhai Jain <anjali.singhai@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>