perf tools: Fix is_bpf_image function logic

Adrian reported that is_bpf_image is not working the way it was intended
- passing on trampolines and dispatcher names. Instead it returned true
for all the bpf names.

The reason even this logic worked properly is that all bpf objects, even
trampolines and dispatcher, were assigned DSO_BINARY_TYPE__BPF_IMAGE
binary_type.

The later for bpf_prog objects, the binary_type was fixed in bpf load
event processing, which is executed after the ksymbol code.

Fixing the is_bpf_image logic, so it properly recognizes trampoline and
dispatcher objects.

Fixes: 3c29d448 ("perf annotate: Add basic support for bpf_image")
Reported-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20200512122310.3154754-1-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/machine.c

@@ -738,8 +738,8 @@ int machine__process_switch_event(struct machine *machine __maybe_unused,
 
 static int is_bpf_image(const char *name)
 {
-	return strncmp(name, "bpf_trampoline_", sizeof("bpf_trampoline_") - 1) ||
-	       strncmp(name, "bpf_dispatcher_", sizeof("bpf_dispatcher_") - 1);
+	return strncmp(name, "bpf_trampoline_", sizeof("bpf_trampoline_") - 1) == 0 ||
+	       strncmp(name, "bpf_dispatcher_", sizeof("bpf_dispatcher_") - 1) == 0;
 }
 
 static int machine__process_ksymbol_register(struct machine *machine,