arm64: dts: msm8996: Add proper capacity scaling for the cpus

msm8996 features 4 cpus - 2 in each cluster. However, all cpus implement
the same microarchitecture and the two clusters only differ in the
maximum frequency attainable by the CPUs.

Add capacity-dmips-mhz property to allow the topology code to determine
the actual capacity by taking into account the highest frequency for
each CPU.

Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Suggested-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Amit Kucheria <amit.kucheria@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Andy Gross <agross@kernel.org>