counter: stm32-timer-cnt: rename quadrature signal

Drop the Quadrature convention in the signal name. On stm32-timer:
- Quadrature A signal corresponds to timer input ch1, hence "Channel 1"
- Quadrature B signal corresponds to timer input ch2, hence "Channel 2".
So name these signals after their channel. I suspect it referred to the
(unique) quadrature counter support earlier, but the physical input
really is CH1/CH2. This will be easier to support other counter modes.

Reviewed-by: William Breathitt Gray <william.gray@linaro.org>
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Link: https://lore.kernel.org/r/20240307133306.383045-2-fabrice.gasnier@foss.st.com


Signed-off-by: William Breathitt Gray <william.gray@linaro.org>