spi: mpc512x: fix error return code in mpc512x_psc_spi_do_probe()

Fix to return a negative error code from the error handling
case instead of 0, as done elsewhere in this function.
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Mark Brown <broonie@linaro.org>

drivers/spi/spi-mpc512x-psc.c

@@ -522,8 +522,10 @@ static int mpc512x_psc_spi_do_probe(struct device *dev, u32 regaddr,
 	psc_num = master->bus_num;
 	snprintf(clk_name, sizeof(clk_name), "psc%d_mclk", psc_num);
 	clk = devm_clk_get(dev, clk_name);
-	if (IS_ERR(clk))
+	if (IS_ERR(clk)) {
+		ret = PTR_ERR(clk);
 		goto free_irq;
+	}
 	ret = clk_prepare_enable(clk);
 	if (ret)
 		goto free_irq;