fix default_keys example for avoid skipping first key

examples/rfid_default_keys/rfid_default_keys.ino

@@ -82,11 +82,6 @@ bool try_key(MFRC522::MIFARE_Key *key)
     byte block = 0;
     MFRC522::StatusCode status;
 
-    // http://arduino.stackexchange.com/a/14316
-    if ( ! mfrc522.PICC_IsNewCardPresent())
-        return false;
-    if ( ! mfrc522.PICC_ReadCardSerial())
-        return false;
     // Serial.println(F("Authenticating using key A..."));
     status = mfrc522.PCD_Authenticate(MFRC522::PICC_CMD_MF_AUTH_KEY_A, block, key, &(mfrc522.uid));
     if (status != MFRC522::STATUS_OK) {
@@ -153,5 +148,11 @@ void loop() {
             // no need to try other keys for this PICC
             break;
         }
+        
+        // http://arduino.stackexchange.com/a/14316
+        if ( ! mfrc522.PICC_IsNewCardPresent())
+            break;
+        if ( ! mfrc522.PICC_ReadCardSerial())
+            break;
     }
 }