xml2sexprtest: Remove graphics from unrelated tests

This caused unnecessary make check failures when libvirt is configured
--with-rhel5-api

tests/xml2sexprdata/xml2sexpr-curmem.xml

@@ -19,6 +19,5 @@
       <source file='/xen/rhel5.img'/>
       <target dev='xvda'/>
     </disk>
-    <graphics type='vnc' port='5905'/>
   </devices>
 </domain>

tests/xml2sexprdata/xml2sexpr-disk-block-shareable.xml

@@ -26,7 +26,6 @@
       <source bridge='xenbr0'/>
       <script path='vif-bridge'/>
     </interface>
-    <graphics type='vnc' port='-1' keymap='en-us'/>
     <console/>
   </devices>
 </domain>