STM32F1: Only include USBComposite if flagged (#15243)

Marlin/src/HAL/HAL_STM32F1/HAL.h

@@ -42,7 +42,10 @@
 #include <util/atomic.h>
 
 #include "../../inc/MarlinConfigPre.h"
-#include "msc_sd.h"
+
+#ifdef USE_USB_COMPOSITE
+  #include "msc_sd.h"
+#endif
 
 // ------------------------
 // Defines
@@ -60,12 +63,6 @@
   #define MSerial4  Serial4
   #define MSerial5  Serial5
 #else
-  #ifndef USE_USB_COMPOSITE
-    extern USBSerial SerialUSB;
-    #define UsbSerial SerialUSB
-  #else
-    #define UsbSerial MarlinCompositeSerial
-  #endif
   #define MSerial1  Serial
   #define MSerial2  Serial1
   #define MSerial3  Serial2

Marlin/src/HAL/HAL_STM32F1/msc_sd.h

@@ -13,7 +13,6 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  *
  */
-
 #pragma once
 
 #include <USBComposite.h>