bnx2x: fix GRO parameters

bnx2x does an internal GRO pass but doesn't provide gso_segs, thus
breaking qdisc_pkt_len_init() in case ingress qdisc is used.

We store gso_segs in NAPI_GRO_CB(skb)->count, where tcp_gro_complete()
expects to find the number of aggregated segments.

Signed-off-by: Yuval Mintz <yuvalmin@broadcom.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>