net-ipv6: Delete an unnecessary check before the function call "free_percpu"

The free_percpu() function tests whether its argument is NULL and then
returns immediately. Thus the test around the call is not needed.

This issue was detected by using the Coccinelle software.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/route.c

@@ -369,10 +369,7 @@ static void ip6_dst_destroy(struct dst_entry *dst)
 	struct inet6_dev *idev;
 
 	dst_destroy_metrics_generic(dst);
-
-	if (rt->rt6i_pcpu)
 	free_percpu(rt->rt6i_pcpu);
-
 	rt6_uncached_list_del(rt);
 
 	idev = rt->rt6i_idev;