iovctl: allow vlan restrictions to be passed to the driver

Allow iovctl to create VFs that are restricted to specific VLAN IDs.

Reviewed by: kib, np
MFC after: 2 weeks
Sponsored by: Orange Business Services
Differential Revision: https://reviews.freebsd.org/D45402

(cherry picked from commit c57c26179033f64c2011a2d2a904ee3fa62e826a)