firmware: arm_sdei: Avoid nested statements in sdei_init()

In sdei_init(), the nested statements can be avoided by bailing
on error from platform_driver_register() or absent ACPI SDEI table.
With it, the code looks a bit more readable.

Signed-off-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: James Morse <james.morse@arm.com>
Link: https://lore.kernel.org/r/20200922130423.10173-5-gshan@redhat.com
Signed-off-by: Will Deacon <will@kernel.org>

Author: Gavin Shan

drivers/firmware/arm_sdei.c

@@ -1081,17 +1081,18 @@ static bool __init sdei_present_acpi(void)
 
 static int __init sdei_init(void)
 {
-	int ret = platform_driver_register(&sdei_driver);
-
-	if (!ret && sdei_present_acpi()) {
-		struct platform_device *pdev;
-
-		pdev = platform_device_register_simple(sdei_driver.driver.name,
-						       0, NULL, 0);
-		if (IS_ERR(pdev))
-			pr_info("Failed to register ACPI:SDEI platform device %ld\n",
-				PTR_ERR(pdev));
-	}
+	struct platform_device *pdev;
+	int ret;
+
+	ret = platform_driver_register(&sdei_driver);
+	if (ret || !sdei_present_acpi())
+		return ret;
+
+	pdev = platform_device_register_simple(sdei_driver.driver.name,
+					       0, NULL, 0);
+	if (IS_ERR(pdev))
+		pr_info("Failed to register ACPI:SDEI platform device %ld\n",
+			PTR_ERR(pdev));
 
 	return ret;
 }