kernel: sched: Fix comparsion in _update_time_slice_before_swap()
kernel: sched: Fix comparsion in _update_time_slice_before_swap()

The _update_time_slice_before_swap() function directly compared
_time_slice_duration (expressed in ms) with value returned by
_get_remaining_program_time() which used ticks as a time unit.

Moreover, the _time_slice_duration was also used as an argument
for _set_time(), which expects time expressed in ticks.

This commit ensures that the same unit (ticks) is used in
comparsion and timer adjustments.

Signed-off-by: Piotr Zięcik <9ef3595b5f0f4fa8d0ceeb52cc0cf0411a0684dd@nordicsemi.no>

Vudentz/zephyr,ldts/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,punitvara/zephyr,nashif/zephyr,Vudentz/zephyr,ldts/zephyr,nashif/zephyr,galak/zephyr,explora26/zephyr,explora26/zephyr,punitvara/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,galak/zephyr,kraj/zephyr,punitvara/zephyr,Vudentz/zephyr,nashif/zephyr,nashif/zephyr,kraj/zephyr,finikorg/zephyr,GiulianoFranchetto/zephyr,ldts/zephyr,punitvara/zephyr,GiulianoFranchetto/zephyr,finikorg/zephyr,finikorg/zephyr,GiulianoFranchetto/zephyr,kraj/zephyr,finikorg/zephyr,Vudentz/zephyr,explora26/zephyr,kraj/zephyr,GiulianoFranchetto/zephyr,Vudentz/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,ldts/zephyr,zephyrproject-rtos/zephyr,explora26/zephyr,ldts/zephyr,explora26/zephyr,GiulianoFranchetto/zephyr,galak/zephyr,punitvara/zephyr,nashif/zephyr,kraj/zephyr,zephyrproject-rtos/zephyr,galak/zephyr