drivers: counter: fix nRF prescaler overflow

[ChristianHirsch]

use u16_t prescaler instead of u8_t prescaler in init_rtc to be able to use the full 12 bit prescaler values.
fixes #22014.

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[carlescufi]

@ChristianHirsch thanks for the PR! Can you follow the instructions here to fix Gitlint?

[pabigot]

I've seen something like this somewhere else very recently. I don't believe there's any benefit to specifying a formal parameter that is smaller than u32_t; in fact there will be a cost, because code must be generated to truncate values to the specified representation. Here nrf_rtc_prescaler_set() takes a u32_t when receiving this value, so it's really unjustified.

I recommend that somebody from Nordic go through all these APIs make sure that an appropriate and standardized size is used when passing values.

[ChristianHirsch]

@pabigot thanks for the hints. should I change the line to u32_t? unfotunately, I did not find any header files to see what nrf_rtc_prescaler_set() expects.
@carlescufi yes, I will fix the Gitlint issues.

[nordic-krch]

looks ok, fix commit message and i'll approve.

should I change the line to u32_t

Please do.

[ioannisg]

@nordic-krch

[ioannisg]

Thanks for your contribution @ChristianHirsch