perf probe: Use dwarf_getcfi_elf() instead of dwarf_getcfi()

The dwarf_getcfi() only checks .debug_frame section for CFI, but as
most binaries only have .eh_frame it'd return NULL and it makes
some variables inaccessible.

Using dwarf_getcfi_elf (along with dwarf_getelf()) allows to show and
add probe to more variables.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Link: http://lkml.kernel.org/r/1396854348-9296-1-git-send-email-namhyung@kernel.org
Signed-off-by: Jiri Olsa <jolsa@redhat.com>