Merge branch 'dsa-MT7530-vlan'

Sean Wang says:

====================
add VLAN support to DSA MT7530

Changes sicne v2:
update to the latest code base from net-next and fix up all building
errors with -Werror.

Changes since v1:
- fix up the typo
- prefer ordering declarations longest to shortest
- update that vlan_prepare callback should not change any state
- use lower case letter for function naming

The patchset extends DSA MT7530 to VLAN support through filling required
callbacks in patch 1 and merging the special tag with VLAN tag in patch 2
for allowing that the hardware can handle these packets with VID from the
CPU port.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>