Fix WebAction mute

WebAction mute was not working since it was setting its current
state instead of the toggling mute.

Change-Id: I9572c77e084e11b00f645845764fe13e0a603664
Reviewed-by: Alexandru Croitor <alexandru.croitor@theqtcompany.com>
Reviewed-by: Joerg Bornemann <joerg.bornemann@theqtcompany.com>