gsupplicant: Rely on wpa_supplicant retry mechanism

When connecting WiFi with a wrong passphrase, connman is longer than
it should to cancel the attempt.

The effect is this change, is to have a quicker feedback to the agent
in charge of passphrase input.

Since, Wpa_supplicant 2.0 and later is already managing its own retry
mechanism, let's use it because it's overkill to have this also
inside comman and even more if it add an unnecessary delay.

Note, that for earlier versions of wpa_supplicant this change may be
reverted, while for later ones (2.0 to HEAD/2013-12-10), it's
resulting a 10 secs improvement (observed the whole test is now 10s
vs 20s between two user's attempts).

Let me credit Liu Guoqiang and Tomasz Bursztyka for helping to solve
this problem.

Fixes CM-655

plugins/wifi.c

@@ -58,8 +58,7 @@
 
 #define CLEANUP_TIMEOUT   8	/* in seconds */
 #define INACTIVE_TIMEOUT  12	/* in seconds */
-#define MAXIMUM_RETRIES   2
-#define FAVORITE_MAXIMUM_RETRIES 4
+#define FAVORITE_MAXIMUM_RETRIES 2
 
 #define BGSCAN_DEFAULT "simple:30:-45:300"
 #define AUTOSCAN_DEFAULT "exponential:3:300"
@@ -1581,8 +1580,7 @@ static bool handle_4way_handshake_failure(GSupplicantInterface *interface,
 	if (connman_service_get_favorite(service)) {
 		if (wifi->retries < FAVORITE_MAXIMUM_RETRIES)
 			return true;
-	} else if (wifi->retries < MAXIMUM_RETRIES)
-		return true;
+	}
 
 	wifi->retries = 0;
 	connman_network_set_error(network, CONNMAN_NETWORK_ERROR_INVALID_KEY);