hw/xen/xen_pt: Add missing license

Commit eaab4d60d3 ("Introduce Xen PCI Passthrough, qdevice")
introduced both xen_pt.[ch], but only added the license to
xen_pt.c. Use the same license for xen_pt.h.

Suggested-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20231114143816.71079-17-philmd@linaro.org>
1 file changed