Avoid name conflict with 'UART'

Marlin/src/core/drivers.h

 #define AXIS_HAS_UART(A) (    AXIS_DRIVER_TYPE(A,TMC2208) \
                            || AXIS_DRIVER_TYPE(A,TMC2209) )
 
+#define AXIS_HAS_RXTX AXIS_HAS_UART
+
 #define AXIS_HAS_SW_SERIAL(A) ((AXIS_HAS_UART(A) && !defined(A##_HARDWARE_SERIAL)))
 
 #define AXIS_HAS_STALLGUARD(A)   (    AXIS_DRIVER_TYPE(A,TMC2130) \
 #define HAS_STALLGUARD     ANY_AXIS_HAS(STALLGUARD)
 #define HAS_SG_RESULT      ANY_AXIS_HAS(SG_RESULT)
 #define HAS_COOLSTEP       ANY_AXIS_HAS(COOLSTEP)
-#define HAS_TMC_UART       ANY_AXIS_HAS(UART)
+#define HAS_TMC_UART       ANY_AXIS_HAS(RXTX)
 #define HAS_TMC_SPI        ANY_AXIS_HAS(SPI)
 #define HAS_TMC_SW_SERIAL  ANY_AXIS_HAS(SW_SERIAL)