USB: defines for USB "Link Power Management" (LPM) ECN

There's a new PM-related change notice for the USB 2.0 specification
called "Link Power Management" (LPM).  It defines a new "L1 Suspend"
state which resembles the current (L2) suspend state, except that it
can be entered and exited much more quickly.  It should thus be more
useful for runtime PM, even though it doesn't mandate reduced power
draw from VBUS.

This patch provides the relevant #defines for usbcore.  Actually
implementing these mechanisms requires host silicon that can generate
new USB packets, plus hubs handling some new requests and peripherals
which understand the new packets.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/core/hcd.h b/drivers/usb/core/hcd.h
index 2d1c3d5e..2c086b8 100644
--- a/drivers/usb/core/hcd.h
+++ b/drivers/usb/core/hcd.h
@@ -28,7 +28,7 @@
 /*
  * USB Packet IDs (PIDs)
  */
-#define USB_PID_UNDEF_0			0xf0
+#define USB_PID_EXT			0xf0	/* USB 2.0 LPM ECN */
 #define USB_PID_OUT			0xe1
 #define USB_PID_ACK			0xd2
 #define USB_PID_DATA0			0xc3