oxfw: Fix whitespace error

According to checkpatch.pl
bebob/oxfw: Simplify PCM rules/constraints
firewire-lib: Add common constraint for PCM substream

PCM constraints are common when drivers use AMDTP streams.
firewire-lib: Expand the time period to 5msec

According to this discussion:
http://mailman.alsa-project.org/pipermail/alsa-devel/2014-April/075696.html