datapath: use vport instead of p

All functions used struct vport *vport except
ovs_vport_find_upcall_portid.

This fixes 1 kerneldoc warning

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Acked-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
datapath: fix a use after free

pskb_may_pull() called by arphdr_ok can change skb->data, so put the arp
setting after arphdr_ok to avoid the use the freed memory

Fixes: 0714812134d7d ("openvswitch: Eliminate memset() from flow_extract.")
Cc: Jesse Gross <jesse@nicira.com>
Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: Li RongQing <roy.qing.li@gmail.com>
Acked-by: Jesse Gross <jesse@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Pravin B Shelar <pshelar@nicira.com>