net: dsa: b53: Restore VLAN entries upon (re)configuration

The first time b53_configure_vlan() is called we have not configured any
VLAN entries yet, since that happens later when interfaces get brought
up. When b53_configure_vlan() is called again from suspend/resume we
need to restore all VLAN entries though.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>