Alsa: Add function to prevent duplicate parts in the visible pa device name string, that occur when the pcm-device name starts with the card name (since they are both used).  Achieved by trimming the pcm-device string beginning.

git-svn-id: http://subversion.assembla.com/svn/portaudio/portaudio/trunk@1908 0f58301d-fd10-0410-b4af-bbb618454e57