This reverts commit 68bffc607f.
After discussing this with Kay we decided to drop this again as by-id
links only make sense for devices that have a unique serial id. If they
don't any attempts to make them unique have the side effect of
nourishing assumptions by users that cannot be met, as the by-id device
link of a device could differ depending on the history of simultaneously
plugged in device.
So, to make sure that all device nodes follow the same rules for by-id/
symlinks, drop this patch again.
If two USB sound cards that have the same serial number are plugged in
make sure the by-id/ device node symlink is unique at least during
runtime, by including the ALSA card id in the symlink name.
This is a followup to ed1b2d9fc7.
Lennart Poettering