PCI/ACPI: Replace open coded variant of resource_union()

Since we have resource_union() helper, let's utilize it here.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Reviewed-by: Hanjun Guo <guohanjun@huawei.com>
Tested-by: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/pci_root.c

@@ -722,9 +722,7 @@ static void acpi_pci_root_validate_resources(struct device *dev,
 			 * our resources no longer match the ACPI _CRS, but
 			 * the kernel resource tree doesn't allow overlaps.
 			 */
-			if (resource_overlaps(res1, res2)) {
-				res2->start = min(res1->start, res2->start);
-				res2->end = max(res1->end, res2->end);
+			if (resource_union(res1, res2, res2)) {
 				dev_info(dev, "host bridge window expanded to %pR; %pR ignored\n",
 					 res2, res1);
 				free = true;