net/ipv6: Remove unncessary check on f6i in fib6_check

Dan reported an imbalance in fib6_check on use of f6i and checking
whether it is null. Since fib6_check is only called if f6i is non-null,
remove the unnecessary check.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/route.c

@@ -2130,8 +2130,7 @@ static bool fib6_check(struct fib6_info *f6i, u32 cookie)
 {
 	u32 rt_cookie = 0;
 
-	if ((f6i && !fib6_get_cookie_safe(f6i, &rt_cookie)) ||
-	     rt_cookie != cookie)
+	if (!fib6_get_cookie_safe(f6i, &rt_cookie) || rt_cookie != cookie)
 		return false;
 
 	if (fib6_check_expired(f6i))