doc: usb: chipidea: add usb wakeup enable example
doc: usb: chipidea: add usb wakeup enable example

Add the example for how to enable USB as system wakeup source.

Signed-off-by: Peter Chen <c01a8c815a4ad165fff2d1c0d35ddf5b16bd3d7b@freescale.com>
Signed-off-by: Greg Kroah-Hartman <4645f7897fd33786a2ee1264d590b3c400559d85@linuxfoundation.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs