atm: use SKB_TRUESIZE() in atm_guess_pdu2truesize()

SKB_TRUESIZE() provides a better approximation of expected skb truesize.

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