Enable 802.11g hardware mode in hostapd.conf

The current hostapd.conf generated by SoftapController does not
contain a hw_mode setting.  As a result hostapd defaults to 802.11b
mode.  This mode is inconsistent with the setting "ieee80211n=1" and
prevents hostapd from using 802.11g/n rates.  Add "hw_mode=g" to the
generated hostapd.conf to allow 802.11g/n rates to be advertised and
used.

Change-Id: Ifd66da3f3ffdfffb7c28e751d20bc432e070b2c3

SoftapController.cpp

@@ -124,7 +124,8 @@ int SoftapController::setSoftap(int argc, char *argv[]) {
     char *fbuf = NULL;
 
     asprintf(&wbuf, "interface=%s\ndriver=nl80211\nctrl_interface="
-            "/data/misc/wifi/hostapd\nssid=%s\nchannel=6\nieee80211n=1\n",
+            "/data/misc/wifi/hostapd\nssid=%s\nchannel=6\nieee80211n=1\n"
+            "hw_mode=g\n",
             argv[2], argv[3]);
 
     if (argc > 4) {