drivers: counter: Rename wrap to top_value

Renamed:
- counter_set_wrap to counter_set_top_value
- counter_get_wrap to counter_get_top_value
- counter_get_max_wrap to counter_get_max_top_value

Updated nRF implementations and counter test.

Signed-off-by: Krzysztof Chruscinski <krzysztof.chruscinski@nordicsemi.no>