len is garbage value in ccnl_ccnb_bytes2pkt in ccnl-pkt-ccnb

[mfrey]

Description

The value of lenin file ccnl-pkt-ccnb.c in line 217 is a garbage value since the variable is never initialized and hence the performed check will fail.

Steps to reproduce the issue

This is a finding of clangs static code analyzer (can be retrieved via running our ./scan-build.sh script)