perf annotate: Fix storing per line sym_hist_entry

perf annotate: Fix storing per line sym_hist_entry

The existing loop incremented the offset while using it as the array
index, when we went to an array of sym_hist_entry instances, we
should've moved the increment to outside of the array element reference,
oops, fix it.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Taeung Song <treeze.taeung@gmail.com>
Cc: Wang Nan <wangnan0@huawei.com>
Fixes: 461c17f00f40 ("perf annotate: Store the sample period in each histogram bucket")
Link: http://lkml.kernel.org/n/tip-s3dm6uyrazlpag3f0psfia07@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>