clockevent: sun4i: Fill the irq field in the clockevent structure

The clock event structure irq field was not filled previously to the
interrupt we're using.

This was resulting in the timer not being used at all when using a
configuration with SMP enabled on a system with several CPUs, and with
the cpumask set to the cpu_possible_mask.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>