Prevent merging of device mapped memory blocks.

This sets the DeviceMapped attribute for GPU-mapped memory blocks,
and prevents merging device mapped blocks. This prevents memory
mapped from the gpu from having its backing address changed by
block coalesce.

src/core/hle/kernel/vm_manager.cpp

@@ -51,6 +51,11 @@ bool VirtualMemoryArea::CanBeMergedWith(const VirtualMemoryArea& next) const {
         type != next.type) {
         return false;
     }
+    if ((attribute & MemoryAttribute::DeviceMapped) == MemoryAttribute::DeviceMapped) {
+        // TODO: Can device mapped memory be merged sanely?
+        // Not merging it may cause inaccuracies versus hardware when memory layout is queried.
+        return false;
+    }
     if (type == VMAType::AllocatedMemoryBlock) {
         return true;
     }