When adding new radio via HWSIM_CMD_NEW_RADIO then listeners on the
multicast group "config" are informed.

While at it, refactor the configuration parameters to be able to
pass them directly and have fewer function arguments.
Signed-off-by: NJukka Rissanen <jukka.rissanen@linux.intel.com>
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>