net/vhost-vdpa: Include missing 'qemu/iov.h' header

vhost-vdpa.c uses methods declared in the "qemu/iov." header. Include it otherwise we get when refactoring unrelated headers: ../net/vhost-vdpa.c: In function ‘vhost_vdpa_net_load_cmd’: ../net/vhost-vdpa.c:714:24: error: implicit declaration of function ‘iov_size’ 714 | size_t data_size = iov_size(data_sg, data_num), cmd_size; | ^~~~~~~~ ../net/vhost-vdpa.c:714:24: error: nested extern declaration of ‘iov_size’ ../net/vhost-vdpa.c:742:5: error: implicit declaration of function ‘iov_from_buf’ 742 | iov_from_buf(out_cursor, 1, 0, &ctrl, sizeof(ctrl)); | ^~~~~~~~~~~~ ../net/vhost-vdpa.c:742:5: error: nested extern declaration of ‘iov_from_buf’ ../net/vhost-vdpa.c:744:5: error: implicit declaration of function ‘iov_to_buf’ 744 | iov_to_buf(data_sg, data_num, 0, | ^~~~~~~~~~ ../net/vhost-vdpa.c:744:5: error: nested extern declaration of ‘iov_to_buf’ ../net/vhost-vdpa.c:748:5: error: implicit declaration of function ‘iov_copy’ 748 | iov_copy(&out, 1, out_cursor, 1, 0, cmd_size); | ^~~~~~~~ Fixes: bd907ae4b00 ("vdpa: manual forward CVQ buffers") Signed-off-by: Philippe Mathieu-Daudé <philmd@oss.qualcomm.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com> Message-Id: <20260812211708.92824-3-philmd@oss.qualcomm.com>