can: hi311x: hi3110_can_probe(): use devm_clk_get_optional() to get the input clock

It's not clear what was the intention of redundant usage of IS_ERR()
around the clock pointer since with the error check of devm_clk_get()
followed by bailout it can't be invalid,

Simplify the code which fetches the input clock by using
devm_clk_get_optional(). It will allow to switch to device properties
approach in the future.

Link: https://lore.kernel.org/all/20211206165542.69887-1-andriy.shevchenko@linux.intel.comSigned-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/spi/hi311x.c

@@ -835,7 +835,7 @@ static int hi3110_can_probe(struct spi_device *spi)
 	struct clk *clk;
 	int freq, ret;
 
-	clk = devm_clk_get(&spi->dev, NULL);
+	clk = devm_clk_get_optional(&spi->dev, NULL);
 	if (IS_ERR(clk)) {
 		dev_err(&spi->dev, "no CAN clock source defined\n");
 		return PTR_ERR(clk);
@@ -851,11 +851,9 @@ static int hi3110_can_probe(struct spi_device *spi)
 	if (!net)
 		return -ENOMEM;
 
-	if (!IS_ERR(clk)) {
 	ret = clk_prepare_enable(clk);
 	if (ret)
 		goto out_free;
-	}
 
 	net->netdev_ops = &hi3110_netdev_ops;
 	net->flags |= IFF_ECHO;
@@ -938,7 +936,6 @@ static int hi3110_can_probe(struct spi_device *spi)
 	hi3110_power_enable(priv->power, 0);
 
  out_clk:
-	if (!IS_ERR(clk))
 	clk_disable_unprepare(clk);
 
  out_free:
@@ -957,7 +954,6 @@ static int hi3110_can_remove(struct spi_device *spi)
 
 	hi3110_power_enable(priv->power, 0);
 
-	if (!IS_ERR(priv->clk))
 	clk_disable_unprepare(priv->clk);
 
 	free_candev(net);