clocksource/drivers/riscv: Events are stopped during CPU suspend

Some implementations of the SBI time extension depend on hart-local
state (for example, CSRs) that are lost or hardware that is powered
down when a CPU is suspended. To be safe, the clockevents driver
cannot assume that timer IRQs will be received during CPU suspend.

Fixes: 62b01943

 ("clocksource: new RISC-V SBI timer driver")
Signed-off-by: Samuel Holland <samuel@sholland.org>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20220509012121.40031-1-samuel@sholland.org
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>