usb: dwc3: Properly set system wakeup

If the device is configured for system wakeup, then make sure that the
xHCI driver knows about it and make sure to permit wakeup only at the
appropriate time.

For host mode, if the controller goes through the dwc3 code path, then a
child xHCI platform device is created. Make sure the platform device
also inherits the wakeup setting for xHCI to enable remote wakeup.

For device mode, make sure to disable system wakeup if no gadget driver
is bound. We may experience unwanted system wakeup due to the wakeup
signal from the controller PMU detecting connection/disconnection when
in low power (D3). E.g. In the case of Steam Deck, the PCI PME prevents
the system staying in suspend.

Cc: stable@vger.kernel.org
Reported-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
Closes: https://lore.kernel.org/linux-usb/70a7692d-647c-9be7-00a6-06fc60f77294@igalia.com/T/#mf00d6669c2eff7b308d1162acd1d66c09f0853c7


Fixes: d07e8819 ("usb: dwc3: add xHCI Host support")
Signed-off-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Tested-by: Sanath S <Sanath.S@amd.com>
Tested-by: Guilherme G. Piccoli <gpiccoli@igalia.com> # Steam Deck
Link: https://lore.kernel.org/r/667cfda7009b502e08462c8fb3f65841d103cc0a.1709865476.git.Thinh.Nguyen@synopsys.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>