[Wraith32] Fix Timer definition in variant

TIM7 does not exist.
TIMER_TONE seems useless for CNC.

Signed-off-by: Frederic Pillon <frederic.pillon@st.com>

Author: fpistm

variants/WRAITH32_F051K6/variant.h

@@ -72,9 +72,7 @@ extern "C" {
 #define PIN_WIRE_SCL            PB6 // 5
 
 // Timer Definitions
-// Use TIM6/TIM7 when possible as servo and tone don't need GPIO output pin
-#define TIMER_TONE              TIM6
-#define TIMER_SERVO             TIM7
+#define TIMER_SERVO             TIM6
 
 // UART Definitions
 #define SERIAL_UART_INSTANCE    2 //Connected to ST-Link