MINOR: quic: Replace MT_LISTs by LISTs for RX packets.

Replace ->rx.pqpkts quic_enc_level struct member MT_LIST by an LIST.
Same thing for ->list quic_rx_packet struct member MT_LIST.
Update the code consequently. This was a reminisence of the multithreading
support (several threads by connection).

Must be backported to 2.6
2 files changed