usb: XHCI: Add support to disable selective suspend

Out of band remote wakeup cannot be used when selective suspend
is enabled as hub driver can resume/suspend the port. Add
support to disable selective suspend on platforms which
does not support usual in-band remote wakeup.

Change-Id: I1bb699c94aed8f61683cc86ff801b50b69872930
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>