[RCAR] Remove meta-rcar-gen3-adas from machine conf

[RCAR] Remove meta-rcar-gen3-adas from machine conf

* Machine h3-salvator-x, m3-salvator-x, ebisu do not
need meta-rcar-gen3-adas. Only board allowing kingfisher
extention need meta-rcar-gen3-adas.

Bug-AGL: SPEC-3463

Change-Id: Id070f9d8ca797aa304a2fb1016ecc65f67f3c44f
Signed-off-by: Ronan Le Martret <ronan.lemartret@iot.bzh>
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/meta-agl/+/24895
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>
Tested-by: Jenkins Job builder account <agl-jobbuilder@automotivelinux.org>