As a preparation to making Hyper-V emulation optional, create a dedicated
kvm_hv_synic_auto_eoi_set() helper to avoid extra ifdefs in lapic.c

No functional change intended.
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Tested-by: Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20231205103630.1391318-5-vkuznets@redhat.comSigned-off-by: Sean Christopherson <seanjc@google.com>