clocksource/drivers/rockchip: Add the dynamic irq flag to the timer

The rockchip timer is a broadcast timer. Add the CLOCK_EVT_FEAT_DYNIRQ flag
and set the cpumask to all possible cpus to save power by avoiding
unnecessary wakeups and IPIs.

Signed-off-by: Huang Tao <huangtao@rock-chips.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Heiko Stuebner <heiko@sntech.de>
Tested-by: Jianqun Xu <jay.xu@rock-chips.com>
Signed-off-by: Caesar Wang <wxt@rock-chips.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>