ARM: dts: qcom: msm8960: add qcom,kpss-wdt-mdm9615

Add specific compatible to timer/watchdog device node.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20221212163532.142533-12-krzysztof.kozlowski@linaro.org