perf/x86/intel/uncore: Fix IIO event constraints for Skylake Server

According to the latest uncore document, COMP_BUF_OCCUPANCY (0xd5) event
can be collected on 2-3 counters. Update uncore IIO event constraints for
Skylake Server.

Fixes: cd34cd97

 ("perf/x86/intel/uncore: Add Skylake server uncore support")
Signed-off-by: Alexander Antonov <alexander.antonov@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Link: https://lore.kernel.org/r/20211115090334.3789-3-alexander.antonov@linux.intel.com