PCI: rcar: Use of_device_get_match_data() to simplify probe

This is a DT-only driver, so the only way to call rcar_pcie_probe() is to
match an entry in rcar_pcie_of_match[], so of_id cannot be NULL.

Furthermore, of_id->data can only be NULL if an rcar_pcie_of_match[] entry
has a NULL .data member.  That's a driver defect, and we don't want to
return -EINVAL, which is easy to ignore.  We'd rather take the NULL pointer
dereference so we notice the problem and fix it.

Use of_device_get_match_data() to retrieve the hw_init_fn pointer.  No
functional change intended.

Suggested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Simon Horman <horms+renesas@verge.net.au>

drivers/pci/host/pcie-rcar.c

@@ -1125,7 +1125,6 @@ static int rcar_pcie_probe(struct platform_device *pdev)
 	struct device *dev = &pdev->dev;
 	struct rcar_pcie *pcie;
 	unsigned int data;
-	const struct of_device_id *of_id;
 	int err;
 	int (*hw_init_fn)(struct rcar_pcie *);
 
@@ -1149,11 +1148,6 @@ static int rcar_pcie_probe(struct platform_device *pdev)
 	if (err)
 		return err;
 
-	of_id = of_match_device(rcar_pcie_of_match, dev);
-	if (!of_id || !of_id->data)
-		return -EINVAL;
-	hw_init_fn = of_id->data;
-
 	pm_runtime_enable(dev);
 	err = pm_runtime_get_sync(dev);
 	if (err < 0) {
@@ -1162,6 +1156,7 @@ static int rcar_pcie_probe(struct platform_device *pdev)
 	}
 
 	/* Failure to get a link might just be that no cards are inserted */
+	hw_init_fn = of_device_get_match_data(dev);
 	err = hw_init_fn(pcie);
 	if (err) {
 		dev_info(dev, "PCIe link down\n");