net: pse-pd: Introduce PSE types enumeration

Introduce an enumeration to define PSE types (C33 or PoDL),
utilizing a bitfield for potential future support of both types.
Include 'pse_get_types' helper for external access to PSE type info.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Kory Maincent <kory.maincent@bootlin.com>
Link: https://lore.kernel.org/r/20240417-feature_poe-v9-2-242293fd1900@bootlin.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>