Revert "zink: allow direct memory mapping for any COHERENT+CACHED buffer"
This reverts commit a3552048. on some drivers this catches qbos, which then hits the below assert. needs more investigation Fixes: a3552048 ("zink: allow direct memory mapping for any COHERENT+CACHED buffer") Part-of: <mesa/mesa!20912> (cherry picked from commit 07809c45)