netkit: Disable netpoll support

netkit: Disable netpoll support

Follow-up to 45160cebd6ac ("net: veth: Disable netpoll support") to
also disable netpoll for netkit interfaces. Same conditions apply
here as well.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Breno Leitao <leitao@debian.org>
Cc: Nikolay Aleksandrov <razor@blackwall.org>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
Reviewed-by: Breno Leitao <leitao@debian.org>
Link: https://lore.kernel.org/r/eab2d69ba2f4c260aef62e4ff0d803e9f60c2c5d.1724414250.git.daniel@iogearbox.net
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>