qlnxe: Allow tapping the TX packets

Currently only the packets in the RX path can be captured by tcpdump
as the ETHER_BPF_MTAP call in the TX path is missing. Add it so that
packets in both directions can be captured.

PR: 290973
Reviewed by: kbowling
MFC after: 5 days
Differential Revision: https://reviews.freebsd.org/D54891