ng_device: add kqueue support

Signed-off-by: Quentin Thébault <quentin.thebault@defenso.fr>

Sponsored by: Defenso
Reviewed by: markj
MFC after: 1 month
Differential Revision: https://reviews.freebsd.org/D52541
Pull Request: https://github.com/freebsd/freebsd-src/pull/1880