sony_acpi: Fix sony_acpi backlight registration and unregistration

Initialize the current brightness if the driver registration
was successful and unregister the driver in the error exit path.
Signed-off-by: Mattia Dongili <malattia@linux.it>
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/acpi/sony_acpi.c

@@ -354,9 +354,14 @@ static int sony_acpi_add(struct acpi_device *device)
 	if (ACPI_SUCCESS(acpi_get_handle(sony_acpi_handle, "GBRT", &handle))) {
 		sony_backlight_device = backlight_device_register("sony", NULL,
 					NULL, &sony_backlight_properties);
+
 	        if (IS_ERR(sony_backlight_device)) {
         	        printk(LOG_PFX "unable to register backlight device\n");
+			sony_backlight_device = NULL;
 		}
+		else
+			sony_backlight_properties.brightness =
+				sony_backlight_get_brightness(sony_backlight_device);
 	}
 
 	for (item = sony_acpi_values; item->name; ++item) {
@@ -400,6 +405,9 @@ static int sony_acpi_add(struct acpi_device *device)
 	return 0;
 
 outproc:
+	if (sony_backlight_device)
+		backlight_device_unregister(sony_backlight_device);
+
 	for (item = sony_acpi_values; item->name; ++item)
 		if (item->proc)
 			remove_proc_entry(item->name, acpi_device_dir(device));