meta-audio-4a-framework: align on eel with latest components revisions

meta-audio-4a-framework: align on eel with latest components revisions

This bump is based on recipes coming for eel branch (revision e029270):

In 4A layer, we now have:
* 4a-softmixer:         SRCREV = "731c21e80ba45339b7dd9b8eae63accd3597d281"
* 4a-hal-unicens:       SRCREV = "${AGL_APP_REVISION}"
* agl-service-audio-4a: SRCREV = "${AGL_APP_REVISION}"
* 4a-hal-generic:       SRCREV = "8142c7ed42167dff7e526952f91909d679453251"
* 4a-mixer:             SRCREV = "${AGL_APP_REVISION}"
* 4a-alsa-core:         SRCREV = "${AGL_APP_REVISION}"

Change-Id: Ib5708e9551f0646e0206deac8795f3b09f5a0569
Signed-off-by: Stephane Desneux <stephane.desneux@iot.bzh>