perf arm spe: Fix uninitialized record error variable

The auxtrace init variable 'err' was not being initialized, leading perf
to abort early in an SPE record command when there was no explicit
error, rather only based whatever memory contents were on the stack.
Initialize it explicitly on getting an SPE successfully, the same way
cs-etm does.

Signed-off-by: Kim Phillips <kim.phillips@arm.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Dongjiu Geng <gengdongjiu@huawei.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Fixes: ffd3d18c20 ("perf tools: Add ARM Statistical Profiling Extensions (SPE) support")
Link: http://lkml.kernel.org/r/20180810174512.52900813e57cbccf18ce99a2@arm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/arch/arm64/util/arm-spe.c

@@ -194,6 +194,7 @@ struct auxtrace_record *arm_spe_recording_init(int *err,
 	sper->itr.read_finish = arm_spe_read_finish;
 	sper->itr.alignment = 0;
 
+	*err = 0;
 	return &sper->itr;
 }