util: Fix memory leak in virPCIProbeStubDriver

Since 9ea90206, @drvpath could be overwritten if we jumped to recheck

Found by Coverity.
Signed-off-by: NJohn Ferlan <jferlan@redhat.com>
Reviewed-by: NPeter Krempa <pkrempa@redhat.com>

src/util/virpci.c

@@ -1018,6 +1018,7 @@ virPCIProbeStubDriver(virPCIStubDriver driver)
             goto cleanup;
         }
 
+        VIR_FREE(drvpath);
         goto recheck;
     }