usbuart: Cleanup of redundant definitions

src/platforms/common/usb_serial.c

@@ -222,7 +222,7 @@ size_t debug_uart_write(const char *buf, const size_t len)
 
 /*
  * Runs deferred processing for AUX serial RX, draining RX FIFO by sending
- * characters to host PC via the debug serial interface. Allowed to write to FIFO OUT pointer.
+ * characters to host PC via the debug serial interface.
  */
 static void debug_uart_send_aux_serial_data(void)
 {

src/platforms/stm32/usbuart.c

@@ -32,12 +32,6 @@
 #include "usb.h"
 #include "aux_serial.h"
 
-#ifdef DMA_STREAM0
-#define DMA_CGIF DMA_ISR_FLAGS
-#else
-#define DMA_CGIF DMA_IFCR_CGIF_BIT
-#endif
-
 #ifdef ENABLE_DEBUG
 /* Debug Fifo buffer with space for copy fn overrun */
 char usb_dbg_buf[AUX_UART_BUFFER_SIZE];