usb: xhci: only set D3hot for pci device

Xhci driver cannot call pci_set_power_state() on non-pci xhci host
controllers. For example, NVIDIA Tegra XHCI host controller which acts
as platform device with XHCI_SPURIOUS_WAKEUP quirk set in some platform
hits this issue during shutdown.

Cc: <stable@vger.kernel.org>
Fixes: 638298dc

 ("xhci: Fix spurious wakeups after S5 on Haswell")
Signed-off-by: Henry Lin <henryl@nvidia.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20191211142007.8847-4-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>