The script did not parse the response properly in case the symbol is
unknown. That version of addr2line responds in two lines:

 ??
 ??:0

but the script was assuming one line ?? ??:0, as returned by addr2line v2.24

Reported-by: Asias He <asias@cloudius-systems.com>
Signed-off-by: Tomasz Grabiec <tgrabiec@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>