fix(timer): STM32U0xx clock source

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

Author: fpistm

libraries/SrcWrapper/src/stm32/timer.c

@@ -629,7 +629,9 @@ uint8_t getTimerClkSrc(TIM_TypeDef *tim)
   uint8_t clkSrc = 0;
 
   if (tim != (TIM_TypeDef *)NC)
-#if defined(STM32C0xx) || defined(STM32F0xx) || defined(STM32G0xx)
+#if defined(STM32C0xx) || defined(STM32F0xx) || defined(STM32G0xx) ||\
+    defined(STM32U0xx)
+
     /* TIMx source CLK is PCKL1 */
     clkSrc = 1;
 #else