soc: arm: nordic: Change tick rate for non-tickless kernel

Set SYS_CLOCK_TICKS_PER_SEC to 128 for non-tickless kernel.
Previously it was set to 32768 disregarding kernel mode and that
lead to too frequent interrupts in non-tickless mode (tick every
30 us). Change to smaller value.

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