can: flexcan: add transceiver capabilities

Currently the flexcan driver does only support adding PHYs by using the
"old" regulator bindings. Add support for CAN transceivers as a PHY. Add
the capability to ensure that the PHY is in operational state when the link
is set to an "up" state.

Signed-off-by: Dimitri Fedrau <dimitri.fedrau@liebherr.com>
Link: https://patch.msgid.link/20250312-flexcan-add-transceiver-caps-v4-2-29e89ae0225a@liebherr.com


Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>