Now allows applying external overlays either in form of
.dts file, literal dts context added to store or precompiled .dtbo.
If overlays are defined, kernel device-trees are compiled with '-@'
so the .dtb files contain symbols which we can reference in our
overlays.
Since `fdtoverlay` doesn't respect `/ compatible` by itself
we query compatible strings of both `dtb` and `dtbo(verlay)`
and apply only if latter is substring of the former.
Also adds support for filtering .dtb files (as there are now nearly 1k
dtbs).
Co-authored-by: georgewhewell <georgerw@gmail.com>
Co-authored-by: Kai Wohlfahrt <kai.wohlfahrt@gmail.com>
