Lock the mutex in the mv88e6xxx_port_vlan_prepare function
called by the DSA stack, instead of doing it in the internal
mv88e6xxx_port_check_hw_vlan helper.
Signed-off-by: Vivien Didelot <vivien.didelot@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>