KVM: x86: Move some EFER bits enablement to common code

KVM: x86: Move some EFER bits enablement to common code

Move EFER bits enablement that only depend on CPU support to common
code, as there is no reason to do it in vendor code. Leave EFER.SVME and
EFER.LMSLE enablement in SVM code as they depend on vendor module
parameters.

Having the enablement in common code ensures that if a vendor starts
supporting an existing feature, KVM doesn't end up advertising to
userspace but not allowing the EFER bit to be set.

No functional change intended.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Yosry Ahmed <yosry@kernel.org>
Link: https://patch.msgid.link/20260307011619.2324234-2-yosry@kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>