MdeModulePkg/NvmExpressHci.c: Save time when BIOS reset with NVMes

Dispatch Shutdown Notification to every NVMe first, then polling
every NVMe t omaake sure all NVMe's shutdown processing is
completed.This will help to save a lot time when BIOS trigger
reset for Servers whose have many NVMes. Tested on a platform
with AMD EPYC cpu with 26 NVMes, this method reduce reset time
from 3 minutes to 10 seconds.

Signed-off-by: Theo <theo.tao@foxmail.com>