net: pse-pd: pd692x0: support disabling disable ports GPIO

net: pse-pd: pd692x0: support disabling disable ports GPIO

Microchip PSE controllers have a dedicated disable ports input that like it
name says disables PoE on all ports.

So lets support parsing that GPIO and using the GPIO flags to set it low
by default and enable PoE on all ports during probe.

Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Robert Marko <robert.marko@sartura.hr>
Reviewed-by: Kory Maincent <kory.maincent@bootlin.com>
Link: https://patch.msgid.link/20260607165600.1260210-2-robert.marko@sartura.hr
Signed-off-by: Jakub Kicinski <kuba@kernel.org>