perf/x86/intel/uncore: Use HRTIMER_MODE_HARD for detecting overflows

hrtimer handlers can be deferred to softirq context and affect timely
detection of counter overflows. Hence switch to HRTIMER_MODE_HARD.

Disabling and re-enabling IRQs in the hrtimer handler is not required
as pmu->start() and pmu->stop() can no longer intervene while updating
event->hw.prev_count.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Sandipan Das <sandipan.das@amd.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/0ad4698465077225769e8edd5b2c7e8f48f636d5.1744906694.git.sandipan.das@amd.com