MB-100: Unbreak dialyzer PLT creation

Remove reference to no longer existent ebin directory.

Change-Id: I907c83bf13a7212d995c2e56d2ebbaf1b3f7ab5b
Reviewed-on: http://review.couchbase.org/27574
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Filipe David Borba Manana <fdmanana@gmail.com>