i.MX6 build tuning issue

During pipewire investigation on HB Edge with the cubox-i build, I realized that its image was not getting the right virtual/pipewire-config package.  Investigation shows that the dynamic package architecture logic in meta-freescale conflicts with AGL's setting of DEFAULTTUNE.  The symptom is some packages end up with '-imx' appended to their architecture, and anything virtual/* will potentially incorrectly come from the '-imx' set of packages.