tablets: more tests coverage

This series is linked to an attempt to fix the generic hid tablets support in the kernel. As such, it won't pass unless the matching series get merged (link to be added).

There are a few cleanups at the beginning of this branch, but the bulk is in 7761f0ad ("tests: tablets: implement better and more covering testing"): instead of manually writing each test and transition, we use a parametrized test to walk through the state machine we expect from the device.

Given that parametrized tests are harder to read when they fail, some output to stdout have been added which help the person debugging the kernel.

Signed-off-by: Benjamin Tissoires benjamin.tissoires@gmail.com

Cc: @whot @nabijaczleweli