Remove restriction on duplicated sound devices in parser

It is perfectly acceptable to have multiple sound devices of
same type in guest configuration. If the underlying hypervisor
does not like this, it is its job to complain, not the XML
parser's

* src/conf/domain_conf.c: Remove hack which deleted duplicated
  sound device models.
* tests/xml2sexprdata/xml2sexpr-fv-sound.xml: Remove duplicate
  models

src/conf/domain_conf.c

@@ -3764,23 +3764,12 @@ static virDomainDefPtr virDomainDefParseXML(virConnectPtr conn,
     if (n && VIR_ALLOC_N(def->sounds, n) < 0)
         goto no_memory;
     for (i = 0 ; i < n ; i++) {
-        int collision = 0, j;
         virDomainSoundDefPtr sound = virDomainSoundDefParseXML(conn,
                                                                nodes[i],
                                                                flags);
         if (!sound)
             goto error;
 
-        /* Verify there's no duplicated sound card */
-        for (j = 0 ; j < def->nsounds ; j++) {
-            if (def->sounds[j]->model == sound->model)
-                collision = 1;
-        }
-        if (collision) {
-            virDomainSoundDefFree(sound);
-            continue;
-        }
-
         def->sounds[def->nsounds++] = sound;
     }
     VIR_FREE(nodes);

tests/xml2sexprdata/xml2sexpr-fv-sound.xml

@@ -32,9 +32,6 @@
     </disk>
     <graphics type='vnc' port='5917' keymap='ja'/>
     <sound model='sb16'/>
-    <sound model='sb16'/>
-    <sound model='es1370'/>
-    <sound model='sb16'/>
     <sound model='es1370'/>
   </devices>
 </domain>