Perf tool errors out with the latest event list for the Ice Lake server.

event syntax error: 'unc_m2m_imc_reads.to_pmm'
                           \___ value too big for format, maximum is 255

The same as the Snow Ridge server, the M2M uncore unit in the Ice Lake
server has the unit mask extension field as well.

Fixes: 2b3b76b5 ("perf/x86/intel/uncore: Add Ice Lake server uncore support")
Reported-by: Jin Yao <yao.jin@linux.intel.com>
Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/1622552943-119174-1-git-send-email-kan.liang@linux.intel.com