The driver assumes that the input selection register (TIM_TISEL) is at
its reset default value. Usually this is the case, but the bootloader
might have modified it.

This bases on a similar patch submitted by Olivier Moysan for pwm-stm32.
Reviewed-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20230413212339.3611722-1-u.kleine-koenig@pengutronix.de/Signed-off-by: William Breathitt Gray <william.gray@linaro.org>