Revert "[Sparc] Leon errata fix passes."

...and the two followup commits:
Revert "[Sparc][Leon] Missed resetting option flags from check-in 278489."
Revert "[Sparc][Leon] Errata fixes for various errata in different
versions of the Leon variants of the Sparc 32 bit processor."

This reverts commit r274856, r278489, and r278492.

llvm-svn: 278511