dt-bindings: watchdog: improve QCOM compatible parsing for modern chips

Parse compatible as expected for modern QCOMs.

Fixes warnings as:
arch/arm64/boot/dts/qcom/sdm845-oneplus-fajita.dt.yaml: watchdog@17980000: compatible: ['qcom,apss-wdt-sdm845', 'qcom,kpss-wdt'] is too long
        From schema: Documentation/devicetree/bindings/watchdog/qcom-wdt.yaml
arch/arm64/boot/dts/qcom/sdm845-oneplus-fajita.dt.yaml: watchdog@17980000: compatible: Additional items are not allowed ('qcom,kpss-wdt' was unexpected)
        From schema: Documentation/devicetree/bindings/watchdog/qcom-wdt.yaml

Signed-off-by: David Heidelberg <david@ixit.cz>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20220111212310.97566-1-david@ixit.cz


Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>