Tweaks to HAL format and order

Marlin/src/HAL/HAL_STM32F1/HAL.h

@@ -73,7 +73,7 @@
   #error "SERIAL_PORT must be from -1 to 3"
 #endif
 #if SERIAL_PORT == -1
-extern USBSerial SerialUSB;
+  extern USBSerial SerialUSB;
   #define MYSERIAL0 SerialUSB
 #elif SERIAL_PORT == 0
   #define MYSERIAL0 Serial
@@ -93,7 +93,7 @@ extern USBSerial SerialUSB;
   #endif
   #define NUM_SERIAL 2
   #if SERIAL_PORT_2 == -1
-  extern USBSerial SerialUSB;
+    extern USBSerial SerialUSB;
     #define MYSERIAL1 SerialUSB
   #elif SERIAL_PORT_2 == 0
     #define MYSERIAL1 Serial