dt-bindings: input: touchscreen: edt-ft5x06: Add ft5426

dt-bindings: input: touchscreen: edt-ft5x06: Add ft5426

Add compatible for ft5426.
Searches for documentation reveal neither edt nor evervision
as some related company, only FocalTech.

Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Oliver Graute <oliver.graute@kococonnector.com>
Link: https://lore.kernel.org/r/20240501204758.758537-2-andreas@kemnade.info
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>