19447: boards/nucleo-f429zi: Provide 2nd timer r=benpicco a=maribu
### Contribution description
- Add a common timer config with two (instead of only one) timer using TIM2 + TIM5
- Mostly copy-pasting the cfg_timer_tim2.h and cfg_timer_tim5.h together
- Make use of that for the `nucleo-f429zi`
### Testing procedure
E.g. `tests/periph_timer`, but also grepping for TIM2 and TIM5 in `boards/nucleo-f429zi/include/periph_conf.h` to detect any conflict e.g. between PWM and timer config.
### Issues/PRs references
None
Co-authored-by: Marian Buschsieweke <marian.buschsieweke@ovgu.de>
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