net/8021q: create device with all possible features in wanted_features

wanted_features is a set of features which have to be enabled if a
hardware allows that.

Currently when a vlan device is created, its wanted_features is set to
current features of its base device.

The problem is that the base device can get new features and they are
not propagated to vlan-s of this device.

If we look at bonding devices, they doesn't have this problem and this
patch suggests to fix this issue by the same way how it works for bonding
devices.

We meet this problem, when we try to create a vlan device over a bonding
device. When a system are booting, real devices require time to be
initialized, so bonding devices created without slaves, then vlan
devices are created and only then ethernet devices are added to the
bonding device. As a result we have vlan devices with disabled
scatter-gather.

* create a bonding device
  $ ip link add bond0 type bond
  $ ethtool -k bond0 | grep scatter
  scatter-gather: off
	tx-scatter-g...