dt-bindings: input: touchscreen: document Himax HX852x(ES)

dt-bindings: input: touchscreen: document Himax HX852x(ES)

Himax HX852x(ES) is a touch panel controller with optional support
for capacitive touch keys.

Unfortunately, the model naming is quite unclear and confusing. There
seems to be a distinction between models (e.g. HX8526) and the "series"
suffix (e.g. -A, -B, -C, -D, -E, -ES). But this doesn't seem to be
applied very consistently because e.g. HX8527-E(44) actually seems to
belong to the -ES series.

The compatible consists of the actual part number followed by the
"series" as fallback compatible. Typically only the latter will be
interesting for drivers as there is no relevant difference on the
driver side.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Link: https://lore.kernel.org/r/20250915-hx852x-v5-1-b938182f1056@linaro.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>