In low-level debugging it might be useful to trace the TPDU state
changes, so let's factor-out the state-setting as a function that
can be amended with printf() or GPIO toggles or the like.
No logical change is introduced here, just assignments replaced with
calling a function that does the assignment. compiler should inline
that.
Change-Id: Ie61321404f3686234c61c68a07d6cb9f5830ddc1