netfilter: xt_set: Check hook mask correctly

Inserting rule before one with SET target we get error with warning in
dmesg(1) output:

  # iptables -A FORWARD -t mangle -j SET --map-set test src --map-prio
  # iptables -I FORWARD 1 -t mangle -j ACCEPT
  iptables: Invalid argument. Run `dmesg' for more information.
  # dmesg |tail -n1
  [268578.026643] mapping of prio or/and queue is allowed only from \
  OUTPUT/FORWARD/POSTROUTING chains

Rather than checking for supported hook bits for SET target check for
unsupported one as done in all rest of matches and targets.

Signed-off-by: Serhey Popovych <serhe.popovych@gmail.com>
Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>