ACPI / PM: Update the copyright notice and description of power.c

The description and copyright notice of drivers/acpi/power.c is out
of date, so update it as appropriate.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/power.c

 /*
- *  acpi_power.c - ACPI Bus Power Management ($Revision: 39 $)
+ * drivers/acpi/power.c - ACPI Power Resources management.
  *
- *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
- *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
+ * Copyright (C) 2001 - 2015 Intel Corp.
+ * Author: Andy Grover <andrew.grover@intel.com>
+ * Author: Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
+ * Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
  *
  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  *
@@ -27,10 +29,11 @@
  * ACPI power-managed devices may be controlled in two ways:
  * 1. via "Device Specific (D-State) Control"
  * 2. via "Power Resource Control".
- * This module is used to manage devices relying on Power Resource Control.
+ * The code below deals with ACPI Power Resources control.
  * 
- * An ACPI "power resource object" describes a software controllable power
- * plane, clock plane, or other resource used by a power managed device.
+ * An ACPI "power resource object" represents a software controllable power
+ * plane, clock plane, or other resource depended on by a device.
+ *
  * A device may rely on multiple power resources, and a power resource
  * may be shared by multiple devices.
  */