arm/mach-at91/pm : fix possible object reference leak

of_find_device_by_node() takes a reference to the struct device
when it finds a match via get_device. When returning error we should
call put_device.
Reviewed-by: Mukesh Ojha <mojha@codeaurora.org>
Signed-off-by: Peng Hao <peng.hao2@zte.com.cn>
Signed-off-by: Ludovic Desroches <ludovic.desroches@microchip.com>

arch/arm/mach-at91/pm.c

@@ -591,13 +591,13 @@ static int __init at91_pm_backup_init(void)
 
 	np = of_find_compatible_node(NULL, NULL, "atmel,sama5d2-securam");
 	if (!np)
-		goto securam_fail;
+		goto securam_fail_no_ref_dev;
 
 	pdev = of_find_device_by_node(np);
 	of_node_put(np);
 	if (!pdev) {
 		pr_warn("%s: failed to find securam device!\n", __func__);
-		goto securam_fail;
+		goto securam_fail_no_ref_dev;
 	}
 
 	sram_pool = gen_pool_get(&pdev->dev, NULL);
@@ -620,6 +620,8 @@ static int __init at91_pm_backup_init(void)
 	return 0;
 
 securam_fail:
+	put_device(&pdev->dev);
+securam_fail_no_ref_dev:
 	iounmap(pm_data.sfrbu);
 	pm_data.sfrbu = NULL;
 	return ret;