net: mvneta: Add xdp tx return bulking support

Convert mvneta driver to xdp_return_frame_bulk APIs.

XDP_REDIRECT (upstream codepath): 275Kpps
XDP_REDIRECT (upstream codepath + bulking APIs): 284Kpps

Co-developed-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/9af8014006d022fc0fec78cdaa71beb56999750d.1605267335.git.lorenzo@kernel.org