ggml-zdnn : mark zDNN buffers as non-host (ggml-org#18967)

While buffers reside in host memory,
additional transformation is needed to use buffers with zDNN.

Fixes ggml-org#18848

Author: AlekseiNikiforovIBM

ggml/src/ggml-zdnn/ggml-zdnn.cpp

@@ -372,7 +372,8 @@ static size_t ggml_backend_zdnn_buffer_type_get_alignment(ggml_backend_buffer_ty
 }
 
 static bool ggml_backend_zdnn_buffer_type_is_host(ggml_backend_buffer_type_t buft) {
-    return true;
+    /* while it resides in host memory, additional transformation is needed */
+    return false;
 
     GGML_UNUSED(buft);
 }