Revert "panfrost: Keep cached BOs mmap'd"

This reverts commit 794c239a990e08b5a42d42607e9c5e5b0921390c.

A kernel bug causes cached BOs to not be unmapped correctly,
triggering "bad page cache" kernel messages and causing short hangs.

Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5355>
1 file changed