xl: field 'type' not set in dm_info

This fixes a bug that makes xl start qemu without the FV/PV specific
options.

From: Jean-Edouard LEJOSNE <jean-edouard.lejosne@citrix.com>
Signed-off-by: Keir Fraser <keir.fraser@citrix.com>
Acked-by: Vincent Hanquez <vincent.hanquez@eu.citrix.com>

tools/libxl/xl.c

@@ -661,6 +661,8 @@ skip_pci:
             dm_info->usbdevice = strdup(buf);
     }
 
+    dm_info->type = c_info->hvm ? XENFV : XENPV;
+
     xlu_cfg_destroy(config);
 }