KVM: api: Pass the devid in the msi routing entry

On ARM, the MSI msg (address and data) comes along with
out-of-band device ID information. The device ID encodes the
device that writes the MSI msg. Let's convey the device id in
kvm_irq_routing_msi and use KVM_MSI_VALID_DEVID flag value in
kvm_irq_routing_entry to indicate the msi devid is populated.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Acked-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>