RDMA/siw: Remove deliver net device event

Since the netdev events of link status is now handled in ib_core,
remove the related code in drivers.

In addition, remove sdev->state as it is only used in siw_query_port(),
and it can be replaced by ib_get_curr_port_state().

Signed-off-by: Yuyu Li <liyuyu6@huawei.com>
Signed-off-by: Junxian Huang <huangjunxian6@hisilicon.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>