Remove an extra word from the H901 error message.
Remove an extra word from the H901 error message.

Change-Id: I3b3ca887a3278bc56326343e8bb2130ca3933100
Reviewed-on: https://review.openstack.org/30821
Reviewed-by: Joe Gordon <e86d445bae62b563de8d927b3d0d3a8cfdae3eea@gmail.com>
Approved: Sean Dague <d7e19930cc1f42c2d0781f4d9e6f1fe5891bf9cf@dague.net>
Reviewed-by: Sean Dague <d7e19930cc1f42c2d0781f4d9e6f1fe5891bf9cf@dague.net>
Approved: Joe Gordon <e86d445bae62b563de8d927b3d0d3a8cfdae3eea@gmail.com>
Tested-by: Jenkins

openstack-dev/hacking,zancas/hacking,hyakuhei/cleantox,hyakuhei/cleantox,zancas/hacking,openstack-dev/hacking