Some network drivers use a non default hard_header_len
Transmitted skb should take into account dev->hard_header_len, or risk
crashes or expensive reallocations.
In the case of aoe, lets reserve MAX_HEADER bytes.
David reported a crash in defxx driver, solved by this patch.
Reported-by: David Oostdyk <daveo@ll.mit.edu> Tested-by: David Oostdyk <daveo@ll.mit.edu> Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Ed Cashin <ecashin@coraid.com> Signed-off-by: David S. Miller <davem@davemloft.net>