mac80211: Fix config variable name for dtim_period

The vif option dtim_period was accidently renamed dtim_interval in r38988
("netifd: add wireless configuration support and port mac80211 to the new
framework"). This is wrong and makes the dtim_period/dtim_interval a dead
option because the rest of the config generation code still uses dtim_period.

Reported-by: Jeppe Ledet-Pedersen <jlp@steinwurf.com>
Signed-off-by: Sven Eckelmann <sven@narfation.org>

SVN-Revision: 41557

package/kernel/mac80211/files/lib/netifd/wireless/mac80211.sh

@@ -53,7 +53,7 @@ drv_mac80211_init_iface_config() {
 	config_add_boolean wds powersave
 	config_add_int maxassoc
 	config_add_int max_listen_int
-	config_add_int dtim_interval
+	config_add_int dtim_period
 
 	# mesh
 	config_add_string mesh_id