net: hns3: remove 1000M/half support of phy

Our phy does not support 1000M/half, this patch removes 1000M/half from
PHY_SUPPORTED_FEATURES.

Signed-off-by: Fuyun Liang <liangfuyun1@huawei.com>
Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>