bts/counter: replace '_' with '-' in counter names

Conform to the convention.

Change-Id: I6162694aae8d354aba318cc1acfdac108239fef0
Reviewed-on: https://gerrit.osmocom.org/103
Tested-by: Jenkins Builder
Reviewed-by: Holger Freyther <holger@freyther.de>
1 file changed