Remove unnecessary group change at meta-agl-bsp for R-Car

Remove unnecessary group change at meta-agl-bsp for R-Car

Current AGL run each process by agl-driver user, that user
need access permission for GPU.  The old AGL use display
group to accept access for GPU, but current agl-driver
user join to video group that is default group for GPU.

This patch remove unnecessary group change at
meta-agl-bsp for R-Car.

Bug-AGL : SPEC-4797

Change-Id: Ife20dea685035b336675304a5c6fc292ed83deb6
Signed-off-by: Naoto Yamaguchi <naoto.yamaguchi@aisin.co.jp>
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/meta-agl/+/28890
Tested-by: Jenkins Job builder account
ci-image-build: Jenkins Job builder account
ci-image-boot-test: Jenkins Job builder account
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>