the inner conditional here didn't include uncached readback, meaning
that many (most?) buffers allocated with uncached memory (i.e., BAR) were
being read back directly instead of using staging resources to be faster
at some point this inner conditional should be reevaluated to determine
whether it still does anything, but this is not that time
fixes, among other things, loading in DOOM2016 on some GPUs
Fixes: 52f27cda05 ("zink: allow direct memory mapping for any COHERENT+CACHED buffer")
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/22907>
Mike Blumenkrantz
24350064ca