Merge pull request #637 from qunfang/slof_dataplane_boot

Add cfg file for a slof case to boot guest with dataplane

qemu/tests/cfg/slof_dataplane_boot.cfg

+- slof_dataplane_boot: install setup image_copy unattended_install.cdrom
+    virt_test_type = qemu
+    type = boot
+    restart_vm = yes
+    kill_vm_on_error = yes
+    login_timeout = 240
+    only ppc64 ppc64le
+    extra_params += " -object iothread,id=iothread0"
+    blk_extra_params_image1 = "iothread=iothread0"