[etherswitch] add support for Marvell 88E6065 ethernet switch incl. 802.1q

This patch brings 802.1q support for Marvell 88E606x ethernet switches.
Test is done on 88E6065 chip (Aterm WR1200).

Submitted by: Hiroki Mori <yamori813@yahoo.co.jp>
Reviewed by: mizhka
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D10144