atl1e: limit gso segment size to prevent generation of wrong ip length fields

[ Upstream commit 31d1670e73f4911fe401273a8f576edc9c2b5fea ]

The limit of 0x3c00 is taken from the windows driver.

Suggested-by: Huang, Xiong <xiong@qca.qualcomm.com>
Cc: Huang, Xiong <xiong@qca.qualcomm.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>