hw/i386/x86-iommu: Fix endianness issue in x86_iommu_irq_to_msi_message()

hw/i386/x86-iommu: Fix endianness issue in x86_iommu_irq_to_msi_message()

The values in "msg" are assembled in host endian byte order (the other
field are also not swapped), so we must not swap the __addr_head here.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20230802135723.178083-6-thuth@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Peter Xu <peterx@redhat.com>