pmdomain: core: Export a common ->sync_state() helper for genpd providers

pmdomain: core: Export a common ->sync_state() helper for genpd providers

In some cases the typical platform driver that act as genpd provider, may
need its own ->sync_state() callback to manage various things. In this
regards, the provider most likely wants to allow its corresponding genpds
to be powered-off.

For this reason, let's introduce a new genpd helper function,
of_genpd_sync_state() that helps genpd provider drivers to achieve this.

Suggested-by: Saravana Kannan <saravanak@google.com>
Reviewed-by: Abel Vesa <abel.vesa@linaro.org>
Tested-by: Hiago De Franco <hiago.franco@toradex.com> # Colibri iMX8X
Tested-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com> # TI AM62A,Xilinx ZynqMP ZCU106
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20250701114733.636510-8-ulf.hansson@linaro.org