Simplify the whole PB fb setup shenanigan (#813)
Simplify the whole PB fb setup shenanigan (#813)

* Simplify the whole PB fb setup shenanigan (and log computations)

Basically doing the same as Kobo/Kindle kernels.
This should hopefully be much saner, and much more compatible.
In case there's any weird corner-cases (einkfb?) or extra-broken
devices, the safety check from #4416 should take care of it.

Frenzie/koreader-base,houqp/koreader-base,NiLuJe/koreader-base,Frenzie/koreader-base,NiLuJe/koreader-base,koreader/koreader-base,houqp/koreader-base,NiLuJe/koreader-base,koreader/koreader-base,houqp/koreader-base,Frenzie/koreader-base,NiLuJe/koreader-base,houqp/koreader-base,koreader/koreader-base,koreader/koreader-base,Frenzie/koreader-base