xhci: remove unnecessary xhci_quiesce call before xhci_halt

Fist function called in xhci_halt is xhci_quiesce, so no point
in calling it twice

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>