REF:https://bugzilla.tianocore.org/show_bug.cgi?id=2948 XhciDxe uses the timer functionality provided by the boot services table to detect timeout conditions. This breaks the driver's ExitBootServices call back, as CoreExitBootServices halts the timer before signaling the ExitBootServices event. If the host controller fails to halt in the call back, the timeout condition will never occur and the boot gets stuck in an indefinite spin loop. Use the free running timer provided by TimerLib to calculate timeouts, avoiding the potential hang. Cc: Hao A Wu <hao.a.wu@intel.com> Cc: Ray Ni <ray.ni@intel.com> Signed-off-by: Patrick Henz <patrick.henz@hpe.com> Reviewed-by: Hao A Wu <hao.a.wu@intel.com>