usb: dwc3: Add support for USB hibernation in host mode

Add support for hibernation of USB in host mode and
cable disconnected mode by adding proper pm operations
freeze and restore.

Change-Id: Ie1761a8afb0bb44a37d6ed4d046e8a09e1f53c5c
Signed-off-by: Sriharsha Allenki <sallenki@codeaurora.org>