agl-service-audiomixer: update SRCREV

agl-service-audiomixer: update SRCREV

Update SRCREV to pick up:

0ff3ef1 Add balance/fade/treble/bass support
5567e12 audiomixer: add new channel volume API
f6eb756 audiomixer: Add gain controls

Bug-AGL: SPEC-5001, SPEC-4931

Change-Id: I2acc5654a3a904fb2245bd0897b99347e589d645
Signed-off-by: Scott Murray <scott.murray@konsulko.com>
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/meta-agl-demo/+/29556
ci-image-boot-test: Jenkins Job builder account
ci-image-build: Jenkins Job builder account
Tested-by: Jenkins Job builder account
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>