KVM: nVMX: Move guest_cpuid_has_evmcs() to hyperv.h

In preparation for making Hyper-V emulation optional, move Hyper-V specific
guest_cpuid_has_evmcs() to hyperv.h.

No functional change intended.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Tested-by: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>
Link: https://lore.kernel.org/r/20231205103630.1391318-12-vkuznets@redhat.com


Signed-off-by: Sean Christopherson <seanjc@google.com>