dice/firewire-lib: Keep dualwire mode but obsolete CIP_HI_DUALWIRE

In post commit, AMDTP functionality in firewire-lib supports mapping
for PCM data channels. With this mapping, firewire-lib can obsolete
a flag, CIP_HI_DUALWIRE, but Dice driver can keep dual wire mode.
firewire-lib: improve packet processing loop for easy reading