meta : handle host views (#30217)
* meta : handle views of tensors allocated on the host
A view shares the memory of its view_src, so ggml-alloc never allocates a view in
the buffer of the split it lands in - the scheduler copies the source into the
split and the ops that use the view read that copy. The view node itself is a noop
and does not need a split of its own, but the meta backend asserted when one was
left inside a meta split:
- ggml_backend_meta_get_split_state() dereferenced tensor->buffer->context
- the graph rebuild mapped every node with ggml_backend_meta_buffer_simple_tensor()
Accept such nodes when they are views of host tensors, which also generalizes the
previous s_copy_main workaround. This fixes the assert hit by KV cache views when
using --split-mode tensor with partial offload.
Assisted-by: pi:llama.cpp/Qwen3.8-Flash-Next
* archs : re-enable sm tensor for K2 Horizon
* cont : add TODO and reference
