MdeModulePkg/SdMmc: update TPL to notify to fix UEFI SCT hang
We have to upgrade the TPL level used by SdMmc stack because the
following flow:
DiskIo2ReadWriteDisk() in logical partition -> PartitionReadBlocksEx()
in logical partition at TPL callback level -> ProbeMediaStatusEx()
with sync request -> DiskIo2ReadWriteDisk() in physical partition ->
waiting for async task completion.
if the low layer driver doesn't run at TPL_NOTIFY level, it will have
no time to trigger async task and cause system hang.