This removes the duplicate include of the transceiver.
The transceiver module is a dependency of the
defaulttransceiver, so an explicite include is not needed
Follow up to #1053
Application developers use `$(USEMODULES)` in their Makefiles to have
the relevant functionally automagically added to their apps. This even
does basic dependency tracking by means of `Makefile.dep`.
But an important thing is missing: the automatic adding of include
paths. This is inconvenient, error prone, and will hinder the RIOT core
developers in future to change folder structures.
