clocksource/drivers/timer-imx-sysctr: Set cpumask to cpu_possible_mask

clocksource/drivers/timer-imx-sysctr: Set cpumask to cpu_possible_mask

The syctr interrupt could set the affinity to any cores in the
SoC. However, the default affinity is set to cpu 0.

This timer will be used as broadcast timer on all the i.MX
SoCs. Because DYNIRQ flag is set, the core time framework will runtime
set the interrupt affinity to the cores that needs to wake up and the
cpumask will runtime set to the core that will be wake up. So even the
sysctr initialization use cpumask 0, there is no issue, the current
patch is just use cpu_possible_mask to show the fact that the timer
supports routed to all the cpu cores and nothing else.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Link: https://lore.kernel.org/r/20211201125030.2307746-2-peng.fan@oss.nxp.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>