The check that map is NULL is already done in the bpf_map__fd(map) and
returns an errno, which does not run further checks.

In addition, even if the check for map is run, the return is a pointer,
which is not consistent with the err_number returned by bpf_map__fd(map).
Signed-off-by: Yang Ruibin <11162571@vivo.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.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>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: opensource.kernel@vivo.com
Link: https://lore.kernel.org/r/20240821101500.4568-1-11162571@vivo.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>