x86: drop further constant cpu_has_* predicates

x86: drop further constant cpu_has_* predicates

EFER and SYSCALL are required on x86-64, and I think there's no point
in assuming there might be no TSC. A few other predicates are simply
unused. Of the ones left but constant I'm not convinced we should drop
them; for some of them we may actually better make them non-constant
(see also next patch in this series).

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>