PM / Domains: Rename pm_genpd_runtime_suspend|resume()

Follow genpd's rule for names of static functions, by renaming
pm_genpd_runtime_suspend|resume() to genpd_runtime_suspend|resume().

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>