fbcon: remove soft scrollback code (missing Doc. patch)

[Phillip Susi]

Daniel Vetter writes:

> Just a quick comment on this: Since most framebuffers are write-combining,
> and reads from that tend to be ~3 orders of magnitude slower than writes
> (at least on the pile of machines I looked at here, there's big
> differences, and some special streaming cpu instructions to make the
> reading side not so slow).
>
> So scrolling by copying tends to be significantly slower than just
> redrawing everything.

I know this was the case years ago with AGP as iirc, it doubled ( 4x, 8x
) the PCI clock rate but only for writes wasn't it?  I thought this was
no longer an issue with PCIe, but if it is, then I guess I'll go ahead
with cleaning up the dead code and having it re-render with the larger
text buffer.