server: softap: Set hw_mode according to selected channel

Change-Id: If3d12d33e857b1438edd504ddbd5e5504673725c
Signed-off-by: Dmitry Shmidt <dimitrysh@google.com>
diff --git a/server/SoftapController.cpp b/server/SoftapController.cpp
index 270bd51..853ca8f 100644
--- a/server/SoftapController.cpp
+++ b/server/SoftapController.cpp
@@ -141,8 +141,8 @@
 
     asprintf(&wbuf, "interface=%s\ndriver=nl80211\nctrl_interface="
             "/data/misc/wifi/hostapd\nssid=%s\nchannel=%d\nieee80211n=1\n"
-            "hw_mode=g\nignore_broadcast_ssid=%d\nwowlan_triggers=any\n",
-            argv[2], argv[3], channel, hidden);
+            "hw_mode=%c\nignore_broadcast_ssid=%d\nwowlan_triggers=any\n",
+            argv[2], argv[3], channel, (channel <= 14) ? 'g' : 'a', hidden);
 
     if (argc > 7) {
         if (!strcmp(argv[6], "wpa-psk")) {