qemu: Remove unnecessary cfg fetch/unref

qemuProcessPrepareDomain has no need to fetch/unref the cfg, so remove it.
Signed-off-by: NJohn Ferlan <jferlan@redhat.com>

src/qemu/qemu_process.c

@@ -5092,7 +5092,6 @@ qemuProcessPrepareDomain(virConnectPtr conn,
     size_t i;
     char *nodeset = NULL;
     qemuDomainObjPrivatePtr priv = vm->privateData;
-    virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
     virCapsPtr caps;
 
     if (!(caps = virQEMUDriverGetCapabilities(driver, false)))
@@ -5188,7 +5187,6 @@ qemuProcessPrepareDomain(virConnectPtr conn,
  cleanup:
     VIR_FREE(nodeset);
     virObjectUnref(caps);
-    virObjectUnref(cfg);
     return ret;
 }