cpufreq: blocklist Qualcomm sm8150 in cpufreq-dt-platdev

The Qualcomm sm8150 platform uses the qcom-cpufreq-hw driver, so
add it to the cpufreq-dt-platdev driver's blocklist.

Signed-off-by: Thara Gopinath <thara.gopinath@linaro.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>