conf: Remove redundant free in virCPUDefFree

vendor_id is (and always was) already freed in virCPUDefFreeModel.

This effectively reverts commit fb49ffc3.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

src/conf/cpu_conf.c

@@ -77,9 +77,6 @@ virCPUDefFree(virCPUDefPtr def)
         return;
 
     virCPUDefFreeModel(def);
-
-    VIR_FREE(def->vendor_id);
-
     VIR_FREE(def);
 }