usbcas.h: use 725 bps for ABC80, which is what ABC800 will generate

USBCAS/usbcas.h

@@ -84,7 +84,7 @@ void fmrx_set_speed(uint32_t baudrate);
 void fmrx_recv_byte(uint8_t byte);
 
 /* Parameters */
-#define CAS_BAUDRATE_ABC80	750
+#define CAS_BAUDRATE_ABC80	725
 #define CAS_BAUDRATE_ABC800	2680
 
 #endif