net: bridge: check __vlan_vid_del for error

Since __vlan_del can return an error code, change its inner function
__vlan_vid_del to return an eventual error from switchdev_port_obj_del.

Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Acked-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>