perf mem: Rework command option handling

Split the common option and ones for record or report.  Otherwise -U in
the record option cannot be used because it clashes with in the common
(or report) option.  Also rename report_events() to __cmd_report() to
follow the convention and to be sync with the record part.

Also set the flag PARSE_OPT_STOP_AT_NON_OPTION for the common option so
that it can show the help message in the subcommand like below:

  $ perf mem record -h

   Usage: perf mem record [<options>] [<command>]
      or: perf mem record [<options>] -- <command> [<options>]

      -C, --cpu <cpu>       list of cpus to profile
      -e, --event <event>   event selector. use 'perf mem record -e list' to list available events
      -f, --force           don't complain, do it
      -K, --all-kernel      collect only kernel level data
      -p, --phys-data       Record/Report sample physical addresses
      -t, --type <type>     memory operations(load,store) Default load,store
      -U, --all-user        collect only user level data
      -v, --verbose         be more verbose (show counter open errors, etc)
          --data-page-size  Record/Report sample data address page size
          --ldlat <n>       mem-loads latency

Cc: Aditya Gupta <adityag@linux.ibm.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: https://lore.kernel.org/r/20240731235505.710436-4-namhyung@kernel.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>