counter: stm32-timer-cnt: Add const qualifier for functions_list array

The struct counter_count functions_list member expects a const enum
counter_count_function array. This patch adds the const qualifier to the
stm32_count_functions to match functions_list.

Cc: Benjamin Gaignard <benjamin.gaignard@st.com>
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Link: https://lore.kernel.org/r/46a1e7096dd9280d8f241894186b3c903956a55f.1623201081.git.vilhelm.gray@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/counter/stm32-timer-cnt.c

@@ -50,7 +50,7 @@ enum stm32_count_function {
 	STM32_COUNT_ENCODER_MODE_3,
 };
 
-static enum counter_count_function stm32_count_functions[] = {
+static const enum counter_count_function stm32_count_functions[] = {
 	[STM32_COUNT_SLAVE_MODE_DISABLED] = COUNTER_COUNT_FUNCTION_INCREASE,
 	[STM32_COUNT_ENCODER_MODE_1] = COUNTER_COUNT_FUNCTION_QUADRATURE_X2_A,
 	[STM32_COUNT_ENCODER_MODE_2] = COUNTER_COUNT_FUNCTION_QUADRATURE_X2_B,