spi: bcm2835aux: remove unneeded NULL check of devm_clk_get

Fix a static code checker warning:
drivers/spi/spi-bcm2835aux.c:460
 bcm2835aux_spi_probe() warn: passing zero to 'PTR_ERR'

In case of error, the function devm_clk_get() returns ERR_PTR()
and not returns NULL.
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-bcm2835aux.c

@@ -456,7 +456,7 @@ static int bcm2835aux_spi_probe(struct platform_device *pdev)
 	}
 
 	bs->clk = devm_clk_get(&pdev->dev, NULL);
-	if ((!bs->clk) || (IS_ERR(bs->clk))) {
+	if (IS_ERR(bs->clk)) {
 		err = PTR_ERR(bs->clk);
 		dev_err(&pdev->dev, "could not get clk: %d\n", err);
 		goto out_master_put;