This reverts commit b8705eb6.

Reason for revert: bf1e47e6 is reverted.

Original change's description:
> PPC64/s390x: move smi to lower 32-bit
> 
> Change-Id: Id203bb297547002a41e18d621b59ce4237f88e5a
> Reviewed-on: https://chromium-review.googlesource.com/1183976
> Reviewed-by: Muntasir Mallick <mmallick@ca.ibm.com>
> Commit-Queue: Junliang Yan <jyan@ca.ibm.com>
> Cr-Commit-Position: refs/heads/master@{#55320}

TBR=jyan@ca.ibm.com,joransiu@ca.ibm.com,mmallick@ca.ibm.com

# Not skipping CQ checks because original CL landed > 1 day ago.

Change-Id: Ied4e7b0cd0659b5429906d1d90c91397fa268416
Reviewed-on: https://chromium-review.googlesource.com/1191162Reviewed-by: Junliang Yan <jyan@ca.ibm.com>
Commit-Queue: Junliang Yan <jyan@ca.ibm.com>
Cr-Commit-Position: refs/heads/master@{#55435}