net/core: lockdep_rtnl_is_held can be boolean

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

In another patch lockdep_is_held is also made return bool.

No functional change.

Signed-off-by: Yaowei Bai <bywxiaobai@163.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index b2258a3..2477595 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -96,7 +96,7 @@
 EXPORT_SYMBOL(rtnl_is_locked);
 
 #ifdef CONFIG_PROVE_LOCKING
-int lockdep_rtnl_is_held(void)
+bool lockdep_rtnl_is_held(void)
 {
 	return lockdep_is_held(&rtnl_mutex);
 }