Resolved Vulnerability: Easier MMIO Mapping Management

Summary

In the Linux kernel, the following vulnerability has been resolved: drm/xe: reset mmio mappings with devm Set our various mmio mappings to NULL. This should make it easier to catch something rogue trying to mess with mmio after device removal. For example, we might unmap everything and then start hitting some mmio address which has already been unmamped by us and then remapped by something else, causing all kinds of carnage.