genirq/timings: Add selftest for irqs circular buffer

After testing the per cpu interrupt circular event, make sure the per
interrupt circular buffer usage is correct.

Add tests to validate the interrupt circular buffer.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: andriy.shevchenko@linux.intel.com
Link: https://lkml.kernel.org/r/20190527205521.12091-8-daniel.lezcano@linaro.org