cipso: correct comments of cipso_v4_cache_invalidate()

Since cipso_v4_cache_invalidate() has no return value, so drop
related descriptions in its comments.

Fixes: 446fda4f ("[NetLabel]: CIPSOv4 engine")
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/cipso_ipv4.c

@@ -187,8 +187,7 @@ static int __init cipso_v4_cache_init(void)
  * cipso_v4_cache_invalidate - Invalidates the current CIPSO cache
  *
  * Description:
- * Invalidates and frees any entries in the CIPSO cache.  Returns zero on
- * success and negative values on failure.
+ * Invalidates and frees any entries in the CIPSO cache.
  *
  */
 void cipso_v4_cache_invalidate(void)