arm64: dts: qcom: sc7280: Add cpuidle states

Add cpuidle states for little and big cpus.
The latency values are preliminary placeholders and will be updated
once testing provides the real numbers.

Signed-off-by: Maulik Shah <mkshah@codeaurora.org>
Signed-off-by: Rajendra Nayak <rnayak@codeaurora.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/1615461961-17716-14-git-send-email-rnayak@codeaurora.org


Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>