can: mcp251x: Fix regulators operation without CONFIG_REGULATOR

If CONFIG_REGULATOR is not set, devm_regulator_get() returns NULL,
so use IS_ERR_OR_NULL() macro for checks.
Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/mcp251x.c

@@ -672,7 +672,7 @@ static int mcp251x_hw_probe(struct spi_device *spi)
 
 static int mcp251x_power_enable(struct regulator *reg, int enable)
 {
-	if (IS_ERR(reg))
+	if (IS_ERR_OR_NULL(reg))
 		return 0;
 
 	if (enable)
@@ -1218,7 +1218,7 @@ static int __maybe_unused mcp251x_can_suspend(struct device *dev)
 		priv->after_suspend = AFTER_SUSPEND_DOWN;
 	}
 
-	if (!IS_ERR(priv->power)) {
+	if (!IS_ERR_OR_NULL(priv->power)) {
 		regulator_disable(priv->power);
 		priv->after_suspend |= AFTER_SUSPEND_POWER;
 	}