et131x: support arbitrary MAX_SKB_FRAGS

This NIC does not support TSO, it is very unlikely it would
have to send packets with many fragments.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20220208004855.1887345-1-eric.dumazet@gmail.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>