perf probe: Add option --symfs

perf probe makes use of debug symbols, so add --symfs as the other
commands have.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: kernel@pengutronix.de
Link: http://lkml.kernel.org/r/1469094512-13440-2-git-send-email-u.kleine-koenig@pengutronix.de


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>