net: hns3: fix error and incorrect format

The pointer type parameter should be declare as const for preventing
from its pointed value being unexpected modified.

The uninitialized variable can not be return directly. The default
return value is 0 if no abnormal result.

This patch fixes the preceding two errors, deletes redundant
declaration of a function and align one parameter.

Signed-off-by: Guojia Liao <liaoguojia@huawei.com>
Signed-off-by: Weihang Li <liweihang@hisilicon.com>
Signed-off-by: Jian Shen <shenjian15@huawei.com>
Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: Huazhong Tan <tanhuazhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>