libvhost-user: fix -Werror=format= on ppc64

libvhost-user: fix -Werror=format= on ppc64

That should fix the following warning:

/home/pm215/qemu/contrib/libvhost-user/libvhost-user.c: In function
‘vu_set_mem_table_exec_postcopy’:
/home/pm215/qemu/contrib/libvhost-user/libvhost-user.c:666:9: error:
format ‘%llx’ expects argument of type ‘long long unsigned int’, but
argument 5 has type ‘__u64’ [-Werror=format=]
         DPRINT("%s: region %d: Registered userfault for %llx + %llx\n",
         ^
/home/pm215/qemu/contrib/libvhost-user/libvhost-user.c:666:9: error:
format ‘%llx’ expects argument of type ‘long long unsigned int’, but
argument 6 has type ‘__u64’ [-Werror=format=]
cc1: all warnings being treated as errors

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20190514104126.6294-3-marcandre.lureau@redhat.com

{ kraxel: s/PRIu64/PRIx64/ ]

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>