AW: Layer 3 status

[Andreas.Eversberg]

> - rslms_recvmsg() frees message if discriminator is not known,
otherwhise it forward it to rslms_rx_rll().
> - rslms_rx_rll() forwards messages to rslms_rx_rll_*_req(), but does
not free it when RLL message type is unknown.

it seems that the message is freed by the receiving layer (or function),
but i cannot understand why layer2_read() in main.c does it after
calling l1ctl_recv.