qemu_domain.c: remove redundant virObjectUnref()

The 'caps' variable in qemuDomainObjPrivateXMLParseAutomaticPlacement()
is set to auto clean via g_autoptr(), but a 'virObjectUnref(caps)' is
being executed in the 'cleanup' label.
Signed-off-by: NDaniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: NMichal Privoznik <mprivozn@redhat.com>

src/qemu/qemu_domain.c

@@ -3106,7 +3106,6 @@ qemuDomainObjPrivateXMLParseAutomaticPlacement(xmlXPathContextPtr ctxt,
     ret = 0;
 
  cleanup:
-    virObjectUnref(caps);
     VIR_FREE(nodeset);
     VIR_FREE(cpuset);