cpufreq: qcom-cpufreq-nvmem: Rename qcs404 data to cpr_genpd

At the moment the CPR genpd based code is named after the qcs404 however
msm8936, msm8939 and other antecedent processors of the qcs404 can also
make use of this data.

Rename it to reflect a more generic use.

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>