netfilter: ipset: Check and reject crazy /0 input parameters

bitmap:ip and bitmap:ip,mac type did not reject such a crazy range
when created and using such a set results in a kernel crash.
The hash types just silently ignored such parameters.

Reject invalid /0 input parameters explicitely.

Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>