cpufreq: qcom-hw: Remove un-necessary cpumask_empty() check

CPUFreq core will always set the "policy->cpus" bitmask with the bitfield
of the CPU that goes first per domain/policy. So there is no way the
"policy->cpus" bitmask will be empty during qcom_cpufreq_hw_cpu_init().

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>