net: pse-pd: Avoid setting max_uA in regulator constraints

Setting the max_uA constraint in the regulator API imposes a current
limit during the regulator registration process. This behavior conflicts
with preserving the maximum PI power budget configuration across reboots.

Instead, compare the desired current limit to MAX_PI_CURRENT in the
pse_pi_set_current_limit() function to ensure proper handling of the
power budget.

Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Kory Maincent <kory.maincent@bootlin.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>