x86/cpufeatures: rename X86_FEATURE_AMD_SSBD to X86_FEATURE_LS_CFG_SSBD

x86/cpufeatures: rename X86_FEATURE_AMD_SSBD to X86_FEATURE_LS_CFG_SSBD

The commit 52817587e706 ('x86/cpufeatures: Disentangle SSBD enumeration') from
upstream disentangles SSBD enumeration. We did not backport that commit because
we did not have what to disentangle on UEK4. Our cpufeature was already
synthetic.

That commit also renames X86_FEATURE_AMD_SSBD to X86_FEATURE_LS_CFG_SSBD. We
need this rename in order to not have conflicting cpu features while
backporting commit 6ac2f49edb1e ('x86/bugs: Add AMD's SPEC_CTRL MSR usage')
from upstream which introduces SPEC_CTRL MSR, which will be the prefered
method.

Orabug: 28870524
CVE: CVE-2018-3639

Signed-off-by: Mihai Carabas <mihai.carabas@oracle.com>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Brian Maly <brian.maly@oracle.com>