Print BLE 128-bit UUIDs according to spec (#2061)

Since the iterator integer counts the bytes backwards we need to
use the complement to 15.

esphome/components/esp32_ble_tracker/esp32_ble_tracker.cpp

@@ -372,7 +372,7 @@ std::string ESPBTUUID::to_string() {
       for (int8_t i = 15; i >= 0; i--) {
         sprintf(bpos, "%02X", this->uuid_.uuid.uuid128[i]);
         bpos += 2;
-        if (i == 3 || i == 5 || i == 7 || i == 9)
+        if (i == 6 || i == 8 || i == 10 || i == 12)
           sprintf(bpos++, "-");
       }
       sbuf[47] = '\0';