mac80211: set new interfaces as idle upon init

Mark new interfaces as idle to allow operations that require that
interfaces are idle to take place. Interface types that are always
not idle (like AP interfaces) will be set as not idle when they are
assigned a channel context.

Signed-off-by: Avraham Stern <avraham.stern@intel.com>
Signed-off-by: Emmanuel <Grumbach&lt;emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>