perf python: Fix NULL vs IS_ERR_OR_NULL() checking

The function trace_event__tp_format_id may return ERR_PTR(-ENOMEM).  Use
IS_ERR_OR_NULL to check tp_format.

Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <song@kernel.org>
Link: http://lore.kernel.org/lkml/20211211053856.19827-1-linmq006@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Author: Yuuoniy

tools/perf/util/python.c

@@ -461,7 +461,7 @@ get_tracepoint_field(struct pyrf_event *pevent, PyObject *attr_name)
 		struct tep_event *tp_format;
 
 		tp_format = trace_event__tp_format_id(evsel->core.attr.config);
-		if (!tp_format)
+		if (IS_ERR_OR_NULL(tp_format))
 			return NULL;
 
 		evsel->tp_format = tp_format;