{cfg,nl,mac}80211: set beacon interval and DTIM period on mesh join

Move the default mesh beacon interval and DTIM period to cfg80211
and make them accessible to nl80211. This enables setting both
values when joining an MBSS.

Previously the DTIM parameter was not set by mac80211 so the
driver's default value was used.

Signed-off-by: Marco Porsch <marco@cozybit.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

include/net/cfg80211.h

@@ -1036,6 +1036,8 @@ struct mesh_config {
  * @ie_len: length of vendor information elements
  * @is_authenticated: this mesh requires authentication
  * @is_secure: this mesh uses security
+ * @dtim_period: DTIM period to use
+ * @beacon_interval: beacon interval to use
  * @mcast_rate: multicat rate for Mesh Node [6Mbps is the default for 802.11a]
  *
  * These parameters are fixed when the mesh is created.
@@ -1051,6 +1053,8 @@ struct mesh_setup {
 	u8 ie_len;
 	bool is_authenticated;
 	bool is_secure;
+	u8 dtim_period;
+	u16 beacon_interval;
 	int mcast_rate[IEEE80211_NUM_BANDS];
 };