net/icmpv6: fix wrong logical operator in recvmsg validation

Change && to || in the fromlen validation of icmpv6_recvmsg().
The original condition (fromlen == NULL && *fromlen < sizeof(...))
would never be true when fromlen is NULL due to short-circuit
evaluation. The correct logic is: reject if fromlen is NULL or
the buffer is too small.

Signed-off-by: zhanghongyu <zhanghongyu@xiaomi.com>

net/icmpv6/icmpv6_recvmsg.c

@@ -325,7 +325,7 @@ ssize_t icmpv6_recvmsg(FAR struct socket *psock, FAR struct msghdr *msg,
 
   if (from != NULL)
     {
-      if (fromlen == NULL && *fromlen < sizeof(struct sockaddr_in6))
+      if (fromlen == NULL || *fromlen < sizeof(struct sockaddr_in6))
         {
           return -EINVAL;
         }