net: fix kmemcheck annotations

struct sk_buff kmemcheck annotations enlarged this structure by 8/16 bytes

Fix this by moving 'protocol' inside flags1 bitfield,
and queue_mapping inside flags2 bitfield.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>