Fix how tier_handler is imported
Fix how tier_handler is imported

Change-Id: I36577ca73042b181b4634c4d6bf3ac5d905fd560
Signed-off-by: Cédric Ollivier <d48310251a4a484d041bc5d09a9ac4d86d20f793@orange.com>

opnfv/functest,mywulin/functest,mywulin/functest,opnfv/functest