wifi: Add listen AP_EVENT_ENABLED event

The WPA_EVENT_CHANNEL_SWITCH only request to send it when channel
switch. It may not receive this event when hotspot started(It depends on
driver's design). Add listen AP_EVENT_ENABLED to handle if driver
doesn't support WPA_EVENT_CHANNEL_SWITCH when hotspot enabled.

Bug: 172536837
Test: Manual test to check behavior in log.
Change-Id: I8d97477da6b96bcd1ec3dbb9d5c560dc54f47bad
diff --git a/hostapd/hidl/1.3/hostapd.cpp b/hostapd/hidl/1.3/hostapd.cpp
index 274a079..ce20cea 100644
--- a/hostapd/hidl/1.3/hostapd.cpp
+++ b/hostapd/hidl/1.3/hostapd.cpp
@@ -841,7 +841,9 @@
 		   enum wpa_msg_type type, const char *txt,
 		   size_t len) {
 		wpa_printf(MSG_DEBUG, "Receive wpa msg : %s", txt);
-		if (os_strncmp(txt, WPA_EVENT_CHANNEL_SWITCH,
+		if (os_strncmp(txt, AP_EVENT_ENABLED,
+			       strlen(AP_EVENT_ENABLED)) == 0 ||
+		    os_strncmp(txt, WPA_EVENT_CHANNEL_SWITCH,
 			       strlen(WPA_EVENT_CHANNEL_SWITCH)) == 0) {
 		    for (const auto &callback : callbacks_) {
 			callback->onApInstanceInfoChanged(