xend: Fix up check "mac" address sooner change

In changeset 21653,
         dev_type = sxp.name(dev_config)
should not have been moved, otherwise, the checking "mac"
paragraph is of no use.

(The original patch as submitted was correct but I had to make the
change manually as it had been mangled.)

Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Signed-off-by Chunyan Liu <CYLiu@novell.com>

tools/python/xen/xend/XendDomainInfo.py

@@ -833,6 +833,8 @@ class XendDomainInfo:
         @type  dev_config: SXP object (parsed config)
         """
         log.debug("XendDomainInfo.device_create: %s" % scrub_password(dev_config))
+        dev_type = sxp.name(dev_config)
+
         if dev_type == 'vif':
             for x in dev_config:
                 if x != 'vif' and x[0] == 'mac':
@@ -840,7 +842,6 @@ class XendDomainInfo:
                         log.error("Virtual network interface creation error - invalid MAC Address entered: %s", x[1])
                         raise VmError("Cannot create a new virtual network interface - MAC address is not valid!");
 
-        dev_type = sxp.name(dev_config)
         dev_uuid = self.info.device_add(dev_type, cfg_sxp = dev_config)
         dev_config_dict = self.info['devices'][dev_uuid][1]
         log.debug("XendDomainInfo.device_create: %s" % scrub_password(dev_config_dict))