dpll: add reference sync get/set

dpll: add reference sync get/set

Define function for reference sync pin registration and callback ops to
set/get current feature state.

Implement netlink handler to fill netlink messages with reference sync
pin configuration of capable pins (pin-get).

Implement netlink handler to call proper ops and configure reference
sync pin state (pin-set).

Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Reviewed-by: Milena Olech <milena.olech@intel.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Arkadiusz Kubalewski <arkadiusz.kubalewski@intel.com>
Link: https://patch.msgid.link/20250626135219.1769350-3-arkadiusz.kubalewski@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>