!1836 tcp: Reduce chance of collisions in inet6_hashfn().

Merge Pull Request from: @ci-robot 
 
PR sync from: Wang Yufen <wangyufen@huawei.com>
https://mailweb.openeuler.org/hyperkitty/list/kernel@openeuler.org/message/P3JACN4MLJW7G5NKTXBTQ46GZ5R5YEBI/ 
 
https://gitee.com/src-openeuler/kernel/issues/I7FUFX 
 
Link:https://gitee.com/openeuler/kernel/pulls/1836 

Reviewed-by: Yue Haibing <yuehaibing@huawei.com> 
Signed-off-by: Liu YongQiang <liuyongqiang13@huawei.com> 

include/net/ipv6.h

@@ -602,12 +602,8 @@ static inline u32 ipv6_addr_hash(const struct in6_addr *a)
 /* more secured version of ipv6_addr_hash() */
 static inline u32 __ipv6_addr_jhash(const struct in6_addr *a, const u32 initval)
 {
-	u32 v = (__force u32)a->s6_addr32[0] ^ (__force u32)a->s6_addr32[1];
-
-	return jhash_3words(v,
-			    (__force u32)a->s6_addr32[2],
-			    (__force u32)a->s6_addr32[3],
-			    initval);
+	return jhash2((__force const u32 *)a->s6_addr32,
+		      ARRAY_SIZE(a->s6_addr32), initval);
 }
 
 static inline bool ipv6_addr_loopback(const struct in6_addr *a)