dt-bindings: input: colibri-vf50-ts: Improve documentation

Clarify properties definition, drop unused pinctrl-2 state 'gpio'.

Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>
Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220712101619.326120-3-francesco.dolcini@toradex.com


Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>