[abis_rsl] Fix rsl_encryption_cmd L3 length computation

msg->l3h doesn't have any coherent value at that point,
can't use that.

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
1 file changed
tree: 809f5c4f49cb97f10e809cee69b670ede312e991
  1. hlrsync/
  2. linux-kernel/
  3. openbsc/
  4. wireshark/