counter: stm32-timer-cnt: add checks on quadrature encoder capability

This is a precursor patch to support capture channels on all possible
channels and stm32 timer types. Original driver was intended to be used
only as quadrature encoder and simple counter on internal clock.

So, add a check on encoder capability, so the driver may be probed for
timer instances without encoder feature. This way, all timers may be used
as simple counter on internal clock, starting from here.

Encoder capability is retrieved by using the timer index (originally in
stm32-timer-trigger driver and dt-bindings). The need to keep backward
compatibility with existing device tree lead to parse aside trigger node.

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/20240307133306.383045-7-fabrice.gasnier@foss.st.com


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