tick/sched: Don't clear ts::next_tick again in can_stop_idle_tick()

The tick sched structure is already cleared from tick_cancel_sched_timer(),
so there is no need to clear that field again.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240225225508.11587-7-frederic@kernel.org