libril: Fix element count

This lines should drop every 5th element (#5,#10,#15,...).
At the moment it is dropping elements #6, #11, #16, as it start from 0
and the list start from 1. So let's match it up.

Thanks to Tobias Heinemann for the idea.

Change-Id: Idc2904040119716e666ea0fe320cde1d45869ee5