perf intel-bts: Fix potential NULL pointer dereference found by the smatch tool

Based on the following report from Smatch, fix the potential NULL
pointer dereference check.

tools/perf/util/intel-bts.c:898
intel_bts_process_auxtrace_info() error: we previously assumed
'session->itrace_synth_opts' could be null (see line 894)

tools/perf/util/intel-bts.c:899
intel_bts_process_auxtrace_info() warn: variable dereferenced before
check 'session->itrace_synth_opts' (see line 898)

tools/perf/util/intel-bts.c
894 if (session->itrace_synth_opts && session->itrace_synth_opts->set) {
895 bts->synth_opts = *session->itrace_synth_opts;
896 } else {
897 itrace_synth_opts__set_default(&bts->synth_opts,
898 session->itrace_synth_opts->default_no_sample);
^^^^^^^^^^^^^^^^^^^^^^^^^^
899 if (session->itrace_synth_opts)
^^^^^^^^^^^^^^^^^^^^^^^^^^
900 bts->synth_opts.thread_stack =
901 session->itrace_synth_opts->thread_stack;
902 }

'session->itrace_synth_opts' is impossible to be a NULL pointer in
intel_bts_process_auxtrace_info(), thus this patch removes the NULL test
for 'session->itrace_synth_opts'.

Signed-off-by: Leo Yan <[e-mail]>
Acked-by: Adrian Hunter <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Andi Kleen <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Mathieu Poirier <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Suzuki Poulouse <[e-mail]>
Cc: [e-mail]
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/intel-bts.c

···
 	if (dump_trace)
 		return 0;
 
-	if (session->itrace_synth_opts && session->itrace_synth_opts->set) {
+	if (session->itrace_synth_opts->set) {
 		bts->synth_opts = *session->itrace_synth_opts;
 	} else {
 		itrace_synth_opts__set_default(&bts->synth_opts,
 				session->itrace_synth_opts->default_no_sample);
-		if (session->itrace_synth_opts)
-			bts->synth_opts.thread_stack =
+		bts->synth_opts.thread_stack =
 				session->itrace_synth_opts->thread_stack;
 	}