Make the baud rate for ABC800 closer to correct (unused anyway)

USBCAS/usbcas.h

@@ -74,6 +74,6 @@ void fmrx_recv_byte(uint8_t byte);
 
 /* Parameters */
 #define CAS_BAUDRATE_ABC80	750
-#define CAS_BAUDRATE_ABC800	2600
+#define CAS_BAUDRATE_ABC800	2680
 
 #endif