regulator: port Linux of_regulator_match ...

Linux regulator drivers like the pfuze and the incoming stpmic make use
of of_regulator_match to parse regulator init data from the device tree.
Port the function over from Linux v5.3, so drivers depending on it can
follow.

As we have no use in barebox for power saving and suspend states, these
parts are omitted.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>