fix sound icon missplacement due to span.fa-stack
fix sound icon missplacement due to span.fa-stack

it seem this is the only button with this css issue. I reset the padding
to prevent the icon to be missplaced.

mohierf/mod-webui,shinken-monitoring/mod-webui,mohierf/mod-webui,mohierf/mod-webui,shinken-monitoring/mod-webui,shinken-monitoring/mod-webui