Address minor review comments raised against previous change
Ic417f6b008fdc769227c7a23bc8e01a2064ce928. Specifically, remove function
recv_packet_completion() and member EpRecvPktMultiple from struct
htc_ep_callbacks.
Change-Id: I431579356664ad6a6274f58352adf8ce273e084f
CRs-Fixed: 2168647