net: pse-pd: pd692x0: Separate configuration parsing from hardware setup

net: pse-pd: pd692x0: Separate configuration parsing from hardware setup

Cache the port matrix configuration in driver private data to enable
PSE controller reconfiguration. This refactoring separates device tree
parsing from hardware configuration application, allowing settings to be
reapplied without reparsing the device tree.

This refactoring is a prerequisite for preserving PSE configuration
across reboots to prevent power disruption to connected devices.

Signed-off-by: Kory Maincent <kory.maincent@bootlin.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20251013-feature_pd692x0_reboot_keep_conf-v2-2-68ab082a93dd@bootlin.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>