ggml : remove redundant n_copies check when setting input/output (#17612)

This commit removes a redundant check for sched->n_copies > 1 when
setting input and output flags on tensor copies in
ggml_backend_sched_split_graph.

The motivation for this change is to clarify the code as the outer if
statement already performs this check.

ggml/src/ggml-backend.cpp

@@ -1240,10 +1240,8 @@ void ggml_backend_sched_split_graph(ggml_backend_sched_t sched, struct ggml_cgra
                                 tensor_copy = ggml_dup_tensor_layout(sched->ctx, src);
                                 ggml_format_name(tensor_copy, "%s#%s#%d", ggml_backend_name(backend), src->name, c);
                             }
-                            if (sched->n_copies > 1) {
-                                ggml_set_input(tensor_copy);
-                                ggml_set_output(tensor_copy); // prevent ggml-alloc from overwriting the tensor
-                            }
+                            ggml_set_input(tensor_copy);
+                            ggml_set_output(tensor_copy); // prevent ggml-alloc from overwriting the tensor
                             tensor_id_copy(src_id, src_backend_id, c) = tensor_copy;
                             SET_CAUSE(tensor_copy, "4.cpy");
                         }