cpufreq: qcom-nvmem: Convert to dev_pm_domain_attach|detach_list()

Rather than hooking up the PM domains through _opp_attach_genpd() and
manually manage runtime PM for the corresponding virtual devices created by
genpd during attach, let's avoid the boilerplate-code by converting into
dev_pm_domain_attach|detach_list.

Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20241002122232.194245-11-ulf.hansson@linaro.org