- Added atmega328p to BOARD_BLACKLIST where needed
- Adapted special timer frequency selection in tests/periph_timer to also
select 25kHz for the atmega328p board
The Arduino Leonardo requires - like the other ATmega based Arduinos - a
different frequency than the default 1000000, as this frequency cannot be
achieved on a 16MHz ATmega with any available prescaler.
Added arduino-nano to BOARD_INSUFFICIENT_MEMORY/BOARD_BLACKLIST following suit
of how arduino-uno is marked, as arduino-nano is mostly an Uno in a different
form factor.
By default the periph_timer tests wants to init all timers with 1MHz,
which is not suitable for all timers, e.g. the atmega timers cannot
run at that speed to make the test work they need to be set to 250kHz.
