usb/xhci: release xhci->lock during turning on/off usb port's acpi power resource...

When setting usb port's acpi power resource, there will be some xhci hub requests.
This will cause dead lock since xhci->lock has been held before setting acpi power
resource in the xhci_hub_control(). The usb_acpi_power_manageable() function might
fall into sleep so release xhci->lock before invoking it.

Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>