Coalesce dmem map

Aligns with hardware observations, hopefully shouldn't break anything since nothing should change hardware-wise when release dmem calls and unmap calls are performed?
Either that or Windows breaks because Windows, will need to test.

src/core/memory.cpp

@@ -182,6 +182,7 @@ PAddr MemoryManager::Allocate(PAddr search_start, PAddr search_end, size_t size,
     auto& area = CarveDmemArea(mapping_start, size)->second;
     area.memory_type = memory_type;
     area.is_free = false;
+    MergeAdjacent(dmem_map, dmem_area);
     return mapping_start;
 }