netlink: cleanup the unnecessary return value check

It's no needed to check the return value of tab since the NULL situation
has been handled already, and the rtnl_msg_handlers[PF_UNSPEC] has been
initialized as non-NULL during the rtnetlink_init().
Signed-off-by: NHans Zhang <zhanghonghui@huawei.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/core/rtnetlink.c

@@ -128,7 +128,7 @@ static rtnl_doit_func rtnl_get_doit(int protocol, int msgindex)
 	if (tab == NULL || tab[msgindex].doit == NULL)
 		tab = rtnl_msg_handlers[PF_UNSPEC];
 
-	return tab ? tab[msgindex].doit : NULL;
+	return tab[msgindex].doit;
 }
 
 static rtnl_dumpit_func rtnl_get_dumpit(int protocol, int msgindex)
@@ -143,7 +143,7 @@ static rtnl_dumpit_func rtnl_get_dumpit(int protocol, int msgindex)
 	if (tab == NULL || tab[msgindex].dumpit == NULL)
 		tab = rtnl_msg_handlers[PF_UNSPEC];
 
-	return tab ? tab[msgindex].dumpit : NULL;
+	return tab[msgindex].dumpit;
 }
 
 static rtnl_calcit_func rtnl_get_calcit(int protocol, int msgindex)
@@ -158,7 +158,7 @@ static rtnl_calcit_func rtnl_get_calcit(int protocol, int msgindex)
 	if (tab == NULL || tab[msgindex].calcit == NULL)
 		tab = rtnl_msg_handlers[PF_UNSPEC];
 
-	return tab ? tab[msgindex].calcit : NULL;
+	return tab[msgindex].calcit;
 }
 
 /**