This reverts commit 9ef888da which is
commit a5b29663 upstream.

It introduced a regression by disabling speculation control when running
under a hypervisor with certain CPUs.

The revert required the removal of a recently added line that cleared
the X86_FEATURE_SSBD CPU capability. The changes to the Atom Merrifield
macro names were preserved since a patch in the SSBD (CVE-2018-3639)
patch set expected the new name.

CVE-2018-3639 (x86)
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
[smb: removed bug link for private 1772128]
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>