meta-agl-bsp: remove imx8mx-evk-viv configuration

meta-agl-bsp: remove imx8mx-evk-viv configuration

Since weston-imx still has not been updated to 13.x, remove the NXP
BSP (i.e. Vivante driver) based configuration for the i.MX8MQ EVK to
avoid confusion.  This can be revisited in the future if NXP catch
up and/or members express interest in supporting older versions of
Weston in agl-compositor.

Bug-AGL: SPEC-5340

Change-Id: I642f43f2c12728f251bbfef2bcfbc77a8d5326be
Signed-off-by: Scott Murray <scott.murray@konsulko.com>
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/meta-agl/+/30769
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>
Tested-by: Jenkins Job builder account
ci-image-build: Jenkins Job builder account