driver: timer: npcx: fix announce/set timer timeout tick

The timer driver doesn't annouce/set the timeout at the tick boundary
but at the absolute next expiration time.
It will cause the accumatlation of the tick drift and cannot pass the
kernel/timer/timer_behavior test suite.
This commit fixes the tick drift problem by annouce the time at the tick
bouandry.

Fixes #59594

Signed-off-by: Jun Lin <CHLin56@nuvoton.com>