net: pse-pd: pd692x0: Add support for PSE PI priority feature

net: pse-pd: pd692x0: Add support for PSE PI priority feature

This patch extends the PSE callbacks by adding support for the newly
introduced pi_set_prio() callback, enabling the configuration of PSE PI
priorities. The current port priority is now also included in the status
information returned to users.

Signed-off-by: Kory Maincent (Dent Project) <kory.maincent@bootlin.com>
Reviewed-by: Oleksij Rempel <o.rempel@pengutronix.de>
Link: https://patch.msgid.link/20250617-feature_poe_port_prio-v14-9-78a1a645e2ee@bootlin.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>