perf lock contention: Use -M for --map-nr-entries

Users often want to change the map size, let's add a short option (-M)
for that.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Hao Luo <haoluo@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <song@kernel.org>
Cc: bpf@vger.kernel.org
Link: https://lore.kernel.org/r/20230406210611.1622492-2-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Documentation/perf-lock.txt

@@ -155,6 +155,7 @@ CONTENTION OPTIONS
 --tid=<value>::
         Record events on existing thread ID (comma separated list).
 
+-M::
 --map-nr-entries=<value>::
 	Maximum number of BPF map entries (default: 10240).
 

tools/perf/builtin-lock.c

@@ -2294,7 +2294,7 @@ int cmd_lock(int argc, const char **argv)
 		   "Trace on existing process id"),
 	OPT_STRING(0, "tid", &target.tid, "tid",
 		   "Trace on existing thread id (exclusive to --pid)"),
-	OPT_CALLBACK(0, "map-nr-entries", &bpf_map_entries, "num",
+	OPT_CALLBACK('M', "map-nr-entries", &bpf_map_entries, "num",
 		     "Max number of BPF map entries", parse_map_entry),
 	OPT_CALLBACK(0, "max-stack", &max_stack_depth, "num",
 		     "Set the maximum stack depth when collecting lopck contention, "