KVM: sefltests: Use CPUID_* instead of X86_FEATURE_* for one-off usage

Rename X86_FEATURE_* macros to CPUID_* in various tests to free up the
X86_FEATURE_* names for KVM-Unit-Tests style CPUID automagic where the
function, leaf, register, and bit for the feature is embedded in its
macro value.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20220614200707.3315957-3-seanjc@google.com