net: pse-pd: pd692x0: Enhance with new current limit and voltage read callbacks

net: pse-pd: pd692x0: Enhance with new current limit and voltage read callbacks

This patch expands PSE callbacks with newly introduced
pi_get/set_current_limit() and pi_get_voltage() callback.
It also add the power limit ranges description in the status returned.
The only way to set ps692x0 port power limit is by configure the power
class plus a small power supplement which maximum depends on each class.

Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Kory Maincent <kory.maincent@bootlin.com>
Link: https://patch.msgid.link/20240704-feature_poe_power_cap-v6-7-320003204264@bootlin.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>