mac80211-hwsim: allow configuring IBSS

mac80211-hwsim: allow configuring IBSS

It will not look standard-compliant in a sniffer
because because it doesn't
 * sync TSF
 * adjust the TSF in beacons
 * send beacons at TBTT
 * cancel beacons when another phy sends

However, it does allow testing the configuration
and parts of the mac80211 code for IBSS and as
such is still useful.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>