mlxsw: spectrum_switchdev: Postpone respin on object deletion

VLAN deletion notifications are emitted before the relevant change is
projected to bridge configuration. Thus, like with VLAN addition,
schedule SPAN respin for later.

Fixes: c520bc69

 ("mlxsw: Respin SPAN on switchdev events")
Signed-off-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>