perf bpf-event: Add missing new line into pr_debug call

perf bpf-event: Add missing new line into pr_debug call

Add a missing new line into pr_debug call in perf_event__synthesize_bpf_events(),
so that the error message does not screw the verbose output.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>
Link: http://lkml.kernel.org/r/20190220122800.864-5-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>