net/inetdevice: bad_mask can be boolean

This patch makes bad_mask return bool due to this particular function
only using either one or zero as its return value.

No functional change.

Signed-off-by: Yaowei Bai <bywxiaobai@163.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
1 file changed