We no longer batch VLAN operations, so there's no need to set the
learning state for a range of VLANs.

Use a common function to set the learning state for a Port-VLAN, thereby
making the code saner more receptive for upcoming changes.
Signed-off-by: NIdo Schimmel <idosch@mellanox.com>
Signed-off-by: NJiri Pirko <jiri@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>