Fix up i.MX8MQ EVK configuration

Fix up i.MX8MQ EVK configuration

Changes:
- Since linux-fslc-lts does not boot on the EVK at the moment,
  and both it and linux-fslc still do not have support for the
  HDMI output, switch back to using linux-fslc-imx with tweaks
  to use etnaviv as we did pre-kirkstone.
- A bbappend has been added for linux-fslc-lts since that was
  missed in a previous upgrade, and even though we are not using
  it now, it is possibly useful for other i.MX variants.
- A machine template for using the NXP BSP with the Vivante GPU
  driver, imx8mq-evk-viv, has been restored, as testing shows it
  now works with the current panel-less homescreens.  As before,
  the intent of this configuration is for testing or as an example
  of potential production use of meta-freescale where NXP support
  is available.
- Start up of Bluetooth support has been disabled, as it currently
  causes kernel oopses or panics (both have been seen in testing).
  This happens with both machine templates.  SPEC-4807 has been
  opened to track this issue.

Bug-AGL: SPEC-4799

Change-Id: I38e4e720643714541efb0fed08d5ab64545bb02d
Signed-off-by: Scott Murray <scott.murray@konsulko.com>
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/meta-agl/+/28937
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>