qemu_v8.mk: Add option to add Xen in boot flow

Introduce option XEN_BOOT to add xen in the bootflow.

When built with XEN_BOOT=y, boot flow currently supported is :

BL1 -> BL2 -> BL31 -> OP-TEE -> uboot -> Xen -> Dom0

xtests can be run over Dom0

Signed-off-by: Ruchika Gupta <ruchika.gupta@linaro.org>
Reviewed-by: Jerome Forissier <jerome@forissier.org>
Acked-by: Jens Wiklander <jens.wiklander@linaro.org>
diff --git a/qemu_v8/xen/xen.cfg b/qemu_v8/xen/xen.cfg
new file mode 100644
index 0000000..4ce3d77
--- /dev/null
+++ b/qemu_v8/xen/xen.cfg
@@ -0,0 +1,7 @@
+[global]
+default=buildroot
+
+[buildroot]
+options=console=dtuart noreboot dom0_mem=1G
+kernel=Image rw root=/dev/ram console=hvc0 earlycon=xenboot
+ramdisk=rootfs.cpio.gz