[VLAN]: Fix hardware rx csum errors

Receiving VLAN packets over a device (without VLAN assist) that is
doing hardware checksumming (CHECKSUM_HW), causes errors because the
VLAN code forgets to adjust the hardware checksum.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>