Fix typos in vnf_base.py
Fix typos in vnf_base.py

Change-Id: Idf0380930e97e1aa4584ba000f32d742a87d9486
Signed-off-by: Cédric Ollivier <d48310251a4a484d041bc5d09a9ac4d86d20f793@orange.com>

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