counter: stm32-timer-cnt: fix a kernel-doc warning

Fix the following warning when documentation is built:
drivers/counter/stm32-timer-cnt.c:37: warning: cannot understand function
prototype: 'enum stm32_count_function'
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Fixes: ad29937e ("counter: Add STM32 Timer quadrature encoder")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/counter/stm32-timer-cnt.c

@@ -28,7 +28,7 @@ struct stm32_timer_cnt {
 };
 
 /**
- * stm32_count_function - enumerates stm32 timer counter encoder modes
+ * enum stm32_count_function - enumerates stm32 timer counter encoder modes
  * @STM32_COUNT_SLAVE_MODE_DISABLED: counts on internal clock when CEN=1
  * @STM32_COUNT_ENCODER_MODE_1: counts TI1FP1 edges, depending on TI2FP2 level
  * @STM32_COUNT_ENCODER_MODE_2: counts TI2FP2 edges, depending on TI1FP1 level