perf record: Allow to specify max stack depth of fp callchain

Currently it has no interface to specify the max stack depth for perf
record.  Extend the command line parameter to accept a number after
'fp' to specify the depth like '--call-graph fp,32'.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Waiman Long <longman@redhat.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20220615163222.1275500-7-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>