NVASGPU: Fix Remap.

src/core/hle/service/nvdrv/devices/nvhost_as_gpu.cpp

@@ -144,6 +144,14 @@ NvResult nvhost_as_gpu::Remap(const std::vector<u8>& input, std::vector<u8>& out
         LOG_DEBUG(Service_NVDRV, "remap entry, offset=0x{:X} handle=0x{:X} pages=0x{:X}",
                   entry.offset, entry.nvmap_handle, entry.pages);
 
+        if (entry.nvmap_handle == 0) {
+            // If nvmap handle is null, we should unmap instead.
+            const auto offset{static_cast<GPUVAddr>(entry.offset) << 0x10};
+            const auto size{static_cast<u64>(entry.pages) << 0x10};
+            system.GPU().MemoryManager().Unmap(offset, size);
+            continue;
+        }
+
         const auto object{nvmap.GetHandle(entry.nvmap_handle)};
         if (!object) {
             LOG_CRITICAL(Service_NVDRV, "invalid nvmap_handle={:X}", entry.nvmap_handle);