CANN: Add ROPE sin/cos cache for reuse (#15912)

* CANN: Add ROPE sin/cos cache for reuse

Introduce sin/cos caching mechanism in ROPE to avoid redundant
computation across layers. The cache is built on the first layer
per device and reused by subsequent layers if parameters match.

- Added sin_cache / cos_cache pointers and position_length tracking
- Introduced cache validity flags and properties:
  (ext_factor, theta_scale, freq_scale, attn_factor, is_neox)
- Accelerates ROPE by eliminating repeated sin/cos generation

This change reduces overhead in multi-layer scenarios while
preserving correctness by verifying parameter consistency.

Co-authored-by: hipudding <huafengchun@gmail.com>

* fix typo

Signed-off-by: noemotiovon <757486878@qq.com>

---------

Signed-off-by: noemotiovon <757486878@qq.com>
Co-authored-by: hipudding <huafengchun@gmail.com>

ggml/src/ggml-cann/ggml-cann.cpp

@@ -2353,6 +2353,9 @@ static enum ggml_status ggml_backend_cann_graph_compute(
     ggml_cann_set_device(cann_ctx->device);
     g_nz_workspaces[cann_ctx->device].clear();
 
+    // calculate rope cache for fist layer in current device.
+    cann_ctx->rope_cache.cached = false;
+
 #ifdef USE_ACL_GRAPH
     bool use_cann_graph = true;
     bool cann_graph_update_required = false;