x86/msi: Allow 15-bit MSI dest_id extension

x86/msi: Allow 15-bit MSI dest_id extension

This is a minimal adaptation and backport of commits:
 • 47bea873cf ("x86/msi: Only use high bits of MSI address for DMAR unit")
 • ab0f59c6f1 ("x86/apic: Support 15 bits of APIC ID in MSI where available")
 • 5a169bf04c ("x86/kvm: Reserve KVM_FEATURE_MSI_EXT_DEST_ID")
 • 2e008ffe42 ("x86/kvm: Enable 15-bit extension when KVM_FEATURE_MSI_EXT_DEST_ID detected")
 • 19e3d60d49 ("x86: Let x2APIC support depend on interrupt remapping or guest support")

This allows APIC IDs up to 32767 and uses the ext dest ID bits in MSI
messages if the KVM hypervisor advertises the capability.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>