oxfw: Fix a bug to add channel constraint

When stream formations have a series of PCM channels like [2,6,2,6],
this constraint doesn't work well.
oxfw: Improve code format and comments
firewire-lib: Add sorting in-packets for full duplex streams with sync

In full duplex streams with synchronization, consistency of SYT field in
in-packets is important for out-packets. This commit add sorting in-packets
according to the value of dbc.