Merge branch 'Remove unused fields in cpumap & devmap'

Hou Tao says:

====================
Patchset "Simplify xdp_do_redirect_map()/xdp_do_flush_map() and XDP
maps" [0] changed per-map flush list to global per-cpu flush list
for cpumap, devmap and xskmap, but it forgot to remove these unused
fields from cpumap and devmap. So just remove these unused fields.

Comments and suggestions are always welcome.

[0]: https://lore.kernel.org/bpf/20191219061006.21980-1-bjorn.topel@gmail.com
====================

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>