MdeModulePkg/NvmExpressDxe: Notify NVME HW when system reset happens

Per NVM Express Spec, software should notify NVME HW when shutdown
occurs.

The NVME controller requires notification for shutdown as part of
its management of internal structures. Even with FUA, failing to
notify the NVME controller to shutdown power off causes the NVME
controller to take quite some time to organize its tables on the
next power on. This time exceeds the normal timeout, so we would
fail to boot the NVME disk.

The host should set the Shutdown Notification (CC.SHN) field to 01b
to indicate a normal shutdown operation. The controller indicates
when shutdown processing is completed by updating the Shutdown Status
(CSTS.SHST) field to 10b.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ruiyu Ni <ruiyu.ni@intel.com>
Reviewed-by: Hao A Wu <hao.a.wu@intel.com>