dt-bindings: net: pse-dt: add bindings for regulator based PoDL PSE controller

Add bindings for the regulator based Ethernet PoDL PSE controller and
generic bindings for all PSE controllers.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>