KVM: x86: Advertise INVPCID by default

Advertise INVPCID by default (if supported by the host kernel) instead
of having both SVM and VMX opt in.  INVPCID was opt in when it was a
VMX only feature so that KVM wouldn't prematurely advertise support
if/when it showed up in the kernel on AMD hardware.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210212003411.1102677-3-seanjc@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>