bnx2x: really disable TPA if 'disable_tpa' option is set

bnx2x's 'disable_tpa=1' module option is not respected properly and TPA
(transparent packet aggregation) remains enabled. Even though the
module option causes LRO to be disabled, TPA is enabled in GRO mode.

Additionally, disabling GRO via ethtool then has no effect. One can
still observe tpa_* statistics increase and large packets being received
in tcpdump.

The bug was an unintended consequence of commit aebf6244 "bnx2x: Be
more forgiving toward SW GRO".

Fix it by following the bp->disable_tpa flag when initializing fp's.

Signed-off-by: Michal Schmidt <mschmidt@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>