net: sched: fix warning in tcindex_alloc_perfect_hash

Syzbot reported warning in tcindex_alloc_perfect_hash. The problem
was in too big cp->hash, which triggers warning in kmalloc. Since
cp->hash comes from userspace, there is no need to warn if value
is not correct

Fixes: b9a24bb7

 ("net_sched: properly handle failure case of tcf_exts_init()")
Reported-and-tested-by:  <syzbot+1071ad60cd7df39fdadb@syzkaller.appspotmail.com>
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Acked-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: David S. Miller <davem@davemloft.net>