mlxsw: spectrum: Fix error return code in mlxsw_sp_port_create()

Fix to return a negative error code from the VID  create error handling
case instead of 0, as done elsewhere in this function.

Fixes: c57529e1

 ("mlxsw: spectrum: Replace vPorts with Port-VLAN")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>