kernel/timeout: Schedule zero-time timeouts
kernel/timeout: Schedule zero-time timeouts

Fix an edge case that snuck in with the recent fix: if timeslicing is
enabled, the CPU's slice_ticks will be zero, and thus match a timeout
object's dticks value of zero, and thus get suppressed (because "we
already have a timeout scheduled for that") incorrectly.

Fixes #31789

Signed-off-by: Andy Ross <c70f9a6bf6ee0cd69c8af4ce5e6b131945769315@intel.com>

nashif/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,galak/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,finikorg/zephyr,Vudentz/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,finikorg/zephyr,Vudentz/zephyr,Vudentz/zephyr,finikorg/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,galak/zephyr,Vudentz/zephyr,Vudentz/zephyr