alsabat returns 0 when more than 1 signal is found and all are near DC

[GitHub issues - opened <github@xxxxxxxxxxxxxxxx>]

alsa-project/alsa-utils issue #114 was opened from hollerdawg:

alsabat should return -EDCONLY (-1002) when only dc signals can be found and there's more than 1 signal but instead returns 0.

Issue URL     : https://github.com/alsa-project/alsa-utils/issues/114
Repository URL: https://github.com/alsa-project/alsa-utils