thinkpad_acpi: Silence an uninitialized variable warning

If fan_get_status() fails then "s" is not initialized.  Tweak the error
handling a bit to silence this warning.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Darren Hart <dvhart@linux.intel.com>

drivers/platform/x86/thinkpad_acpi.c

@@ -7972,10 +7972,12 @@ static int fan_get_status_safe(u8 *status)
 		fan_update_desired_level(s);
 	mutex_unlock(&fan_mutex);
 
+	if (rc)
+		return rc;
 	if (status)
 		*status = s;
 
-	return rc;
+	return 0;
 }
 
 static int fan_get_speed(unsigned int *speed)