can: rcar_can: rcar_can_resume(): fix s2ram with PSCI

can: rcar_can: rcar_can_resume(): fix s2ram with PSCI

On R-Car Gen3 using PSCI, s2ram powers down the SoC.  After resume, the
CAN interface no longer works, until it is brought down and up again.

Fix this by calling rcar_can_start() from the PM resume callback, to
fully initialize the controller instead of just restarting it.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://patch.msgid.link/699b2f7fcb60b31b6f976a37f08ce99c5ffccb31.1755165227.git.geert+renesas@glider.be
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>