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 <[e-mail]>
Link: https://patch.msgid.link/699b2[e-mail]
Signed-off-by: Marc Kleine-Budde <[e-mail]>

drivers/net/can/rcar/rcar_can.c

···
 {
 	struct net_device *ndev = dev_get_drvdata(dev);
 	struct rcar_can_priv *priv = netdev_priv(ndev);
-	u16 ctlr;
 	int err;
 
 	if (!netif_running(ndev))
···
 		return err;
 	}
 
-	ctlr = readw(&priv->regs->ctlr);
-	ctlr &= ~RCAR_CAN_CTLR_SLPM;
-	writew(ctlr, &priv->regs->ctlr);
-	ctlr &= ~RCAR_CAN_CTLR_CANM;
-	writew(ctlr, &priv->regs->ctlr);
-	priv->can.state = CAN_STATE_ERROR_ACTIVE;
+	rcar_can_start(ndev);
 
 	netif_device_attach(ndev);
 	netif_start_queue(ndev);