net: wan: add some required spaces

Add space required before the open parenthesis '(',
and add spaces required around that '<', '>' and '!='.

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>