perf callchain: Use a common function to resolve symbol or name

Refactor the duplicated code to resolve the symbol name or
the address of a symbol into a single function.

Used in next patch to add common functionality.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1415844328-4884-6-git-send-email-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>