openvswitch: fix variable names in comment

 *    - skb->network_header: just past the Ethernet header, or just past the

 *      VLAN header, to the first byte of the Ethernet payload.

 *

 *    - skb->transport_header: If key->dl_type is ETH_P_IP or ETH_P_IPV6

 *    - skb->transport_header: If key->eth.type is ETH_P_IP or ETH_P_IPV6

 *      on output, then just past the IP header, if one is present and

 *      of a correct length, otherwise the same as skb->network_header.

 *      For other key->dl_type values it is left untouched.

 *      For other key->eth.type values it is left untouched.

 */

int ovs_flow_extract(struct sk_buff *skb, u16 in_port, struct sw_flow_key *key,

		 int *key_lenp)