net: stmmac: platform: use optional clk/reset get APIs

Use the devm_reset_control_get_optional() and devm_clk_get_optional()
rather than open coding them.
Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
Link: https://lore.kernel.org/r/20201112092606.5173aa6f@xhacker.debianSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c

@@ -399,6 +399,7 @@ stmmac_probe_config_dt(struct platform_device *pdev, const char **mac)
 	struct device_node *np = pdev->dev.of_node;
 	struct plat_stmmacenet_data *plat;
 	struct stmmac_dma_cfg *dma_cfg;
+	void *ret;
 	int rc;
 
 	plat = devm_kzalloc(&pdev->dev, sizeof(*plat), GFP_KERNEL);
@@ -576,12 +577,10 @@ stmmac_probe_config_dt(struct platform_device *pdev, const char **mac)
 		clk_prepare_enable(plat->stmmac_clk);
 	}
 
-	plat->pclk = devm_clk_get(&pdev->dev, "pclk");
+	plat->pclk = devm_clk_get_optional(&pdev->dev, "pclk");
 	if (IS_ERR(plat->pclk)) {
-		if (PTR_ERR(plat->pclk) == -EPROBE_DEFER)
+		ret = plat->pclk;
 		goto error_pclk_get;
-
-		plat->pclk = NULL;
 	}
 	clk_prepare_enable(plat->pclk);
 
@@ -596,14 +595,11 @@ stmmac_probe_config_dt(struct platform_device *pdev, const char **mac)
 		dev_dbg(&pdev->dev, "PTP rate %d\n", plat->clk_ptp_rate);
 	}
 
-	plat->stmmac_rst = devm_reset_control_get(&pdev->dev,
+	plat->stmmac_rst = devm_reset_control_get_optional(&pdev->dev,
 							   STMMAC_RESOURCE_NAME);
 	if (IS_ERR(plat->stmmac_rst)) {
-		if (PTR_ERR(plat->stmmac_rst) == -EPROBE_DEFER)
+		ret = plat->stmmac_rst;
 		goto error_hw_init;
-
-		dev_info(&pdev->dev, "no reset control found\n");
-		plat->stmmac_rst = NULL;
 	}
 
 	return plat;
@@ -613,7 +609,7 @@ stmmac_probe_config_dt(struct platform_device *pdev, const char **mac)
 error_pclk_get:
 	clk_disable_unprepare(plat->stmmac_clk);
 
-	return ERR_PTR(-EPROBE_DEFER);
+	return ret;
 }
 
 /**