debian: Fix debian packaging build failures due to dot-files in tree.

openvswitch/* no longer matches all the files since commit 826bc7b61345a5d
(build: Add travis continuous integration support) added files with names
beginning with ".".

VMware-BZ: #1298353
Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Justin Pettit <jpettit@nicira.com>