tests: fix centos detection

Type: fix
Fixes: defde0f870

Change-Id: Ib81e3610bd0fc22901a902dc76692f1951ead2b8
Signed-off-by: Klement Sekera <ksekera@cisco.com>
diff --git a/test/framework.py b/test/framework.py
index 307da8f..c049b1a 100644
--- a/test/framework.py
+++ b/test/framework.py
@@ -218,7 +218,7 @@
     return True if "centos" in os_id.lower() else False
 
 
-running_on_centos = _running_on_centos
+running_on_centos = _running_on_centos()
 
 
 class KeepAliveReporter(object):