Properly implement Rotate Right sequence for S390, to use the 64-bit
RLLG instruction.

R=jyan@ca.ibm.com,michael_dawson@ca.ibm.com,mbrandy@us.ibm.com
BUG=

Review URL: https://codereview.chromium.org/1842093003

Cr-Commit-Position: refs/heads/master@{#35142}