The CodeGenerator sequence for kS390_Div64 was incorrectly defaulting
to the 32-bit divide sequence.  That case has been fixed to use the
proper 64-bit divide (DSGR).

Fix bug in DLGR simulation where the register number was being used as
operands instead of the values in those registers.

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

Review URL: https://codereview.chromium.org/1844563002

Cr-Commit-Position: refs/heads/master@{#35110}