This moves the following modules to a architecture-specific Makefile.dep
file:
- cortexm_common
- cortexm_common_periph
- newlib
- newlib_nano
- periph
Uses timer freerunning counter mode (TFC) and updating an internal
reference point instead of relying on RTT for reference time. The
target accuracy has been greatly improved for all test cases in
bench_periph_timer