usb: f_cdev: USB remote wake up feature implementation for DUN

Implement usb remote wake up feature for DUN on sdx55.
For super speed this feature supports wake up of a
particular function from suspend, where as for high speed,
remote wakeup doesn't support wakeup of a particular function
from suspend, but entire usb bus needs to wakeup.

Change-Id: Ia4392fbb65c9302926d26f13f7f776d6bdbdccaf
Signed-off-by: Rohith Kollalsi <rkollals@codeaurora.org>