clocksource/drivers/arm_arch_timer: Remove unnecessary ‘0’ values from irq

The irq variable is initialized whatever the code path, it is poinless
to initialize when declaring it.

Signed-off-by: Li kunyu <kunyu@nfschina.com>
Link: https://lore.kernel.org/r/20240705040729.21961-1-kunyu@nfschina.com


Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>