clocksource/drivers/timer-riscv: Stop stimecmp when cpu hotplug

Stop the timer when the cpu is going to be offline otherwise the
timer interrupt may be pending while performing power-down.

Suggested-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/lkml/20240829033904.477200-3-nick.hu@sifive.com/T/#u
Signed-off-by: Nick Hu <nick.hu@sifive.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20250219114135.27764-3-nick.hu@sifive.com
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>

drivers/clocksource/timer-riscv.c

@@ -126,7 +126,13 @@ static int riscv_timer_starting_cpu(unsigned int cpu)
 
 static int riscv_timer_dying_cpu(unsigned int cpu)
 {
+	/*
+	 * Stop the timer when the cpu is going to be offline otherwise
+	 * the timer interrupt may be pending while performing power-down.
+	 */
+	riscv_clock_event_stop();
 	disable_percpu_irq(riscv_clock_event_irq);
+
 	return 0;
 }