net: marvell: prestera: fix uninitialized vid in prestera_port_vlans_add

prestera_bridge_port_vlan_add should have been called with vlan->vid,
however this was masked by the presence of the local vid variable and I
did not notice the build warning.

Reported-by: kernel test robot <lkp@intel.com>
Fixes: b7a9e0da

 ("net: switchdev: remove vid_begin -> vid_end range from VLAN objects")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Taras Chornyi <tchornyi@marvell.com>
Link: https://lore.kernel.org/r/20210114083556.2274440-1-olteanv@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>