x86/cpufeatures: Assign dedicated feature word for CPUID_0x8000001F[EAX]

x86/cpufeatures: Assign dedicated feature word for CPUID_0x8000001F[EAX]

Collect the scattered SME/SEV related feature flags into a dedicated
word.  There are now five recognized features in CPUID.0x8000001F.EAX,
with at least one more on the horizon (SEV-SNP).  Using a dedicated word
allows KVM to use its automagic CPUID adjustment logic when reporting
the set of supported features to userspace.

No functional change intended.

Signed-off-by: Sean Christopherson <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Reviewed-by: Brijesh Singh <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]