mac80211_hwsim: Add radar bandwidths to the P2P Device combination

Add radar_detect_widths to the interface combination that allows
concurrent P2P Device dedicated interface and AP interfaces, to enable
testing of radar detection when P2P Device interface is used.

Clear the radar_detect_widths in case of multi channel contexts
as this is not currently supported.

As radar_detect_widths are now supported in all combinations,
remove the hwsim_if_dfs_limits definition since it is no longer
needed.

Signed-off-by: Ilan Peer <ilan.peer@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>