perf report: Add missing perf_hpp__init for pipe-mode

perf report: Add missing perf_hpp__init for pipe-mode

The perf_hpp__init() function was only called from setup_browser() so
that the pipe-mode missed the initialization thus didn't respond to
related options.  Fix it.

Reported-by: Robert Richter <robert.richter@amd.com>
Tested-by: Robert Richter <robert.richter@amd.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-tip-commits@vger.kernel.org
Link: http://lkml.kernel.org/r/87txv28spl.fsf_-_@sejong.aot.lge.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>