perf test: Restrict uniquifying test to machines with 'uncore_imc'

perf test: Restrict uniquifying test to machines with 'uncore_imc'

The test would fail if target machine does not have 'uncore_imc'
devices.

Since event uniquifying behavior is similar among different
architectures, we are restricting the test to only run on machines with
`uncore_imc` devices.

Suggested-by: Ian Rogers <irogers@google.com>
Signed-off-by: Chun-Tse Shao <ctshao@google.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250521224513.1104129-1-ctshao@google.com
[ Skip the test, i.e. return 2, instead of returning 0 as if the test had succeed ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>