[alsa] fix initialisation of io functions for capture only mode
[alsa] fix initialisation of io functions for capture only mode

this is a quick fix for the problem reported by Felix Pfeifer.
whitespace cleanup and more thorough fixes of this code follow.

git-svn-id: 9d792367086e53bac42cb25f723fe47762daf29a@4193 0c269be4-1314-0410-8aa9-9f06e86f4224

adiknoth/tschack,drobilla/jack1,ventosus/jack1,ventosus/jack1,drobilla/jack1,ventosus/jack1,drobilla/jack1,adiknoth/tschack,drobilla/jack1,ventosus/jack1