Revert "Engage GHASH for PowerISA 2.07."

This reverts commit 14aaf883d93fb2e321ef1fe25f687fb7b62ef8fe.
Revert "Add GHASH for PowerISA 2.07."

This reverts commit 927f2e5dea1da17bcc2c3d2baf7258318b57515c.