usb: f_cdev: Retry USB function wakeup if USB is into low power mode

Consider case where USB is into low power mode after receiving USB
function suspend from host. To invoke function remote wakeup USB
controller is rerquired to bring out of low power mode. Hence once
USB controller and USB bus is resumed, perform USB function wakeup
from composite_resume() context to resume USB function on host side.

Change-Id: If15b70bc7d3781bc26bf593e3ee3edef621f72d7
Signed-off-by: Mayank Rana <mrana@codeaurora.org>