This patch adds the following support to the HNS3 driver:
1. Support to change the Maximum Transmission Unit of a
   port in the HNS NIC hardware.
2. Initializes the supported MTU range for the netdevice.
Signed-off-by: Nlipeng <lipeng321@huawei.com>
Signed-off-by: NSalil Mehta <salil.mehta@huawei.com>
Reviewed-by: NAndrew Lunn <andrew@lunn.ch>
Reviewed-by: NLeon Romanovsky <leonro@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>