net: ixp4xx_hss: add some required spaces

Add space required before the open parenthesis '('.
Add space required after that close brace '}'.

Signed-off-by: Peng Li <lipeng321@huawei.com>
Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>