[A5][bugfix] Fix fused MoE A5 MXFP8 scale normalization, load-balance routing and gating_topk ops (#7573)

### What this PR does / why we need it?
This PR fixes A5 MXFP8 MoE scale handling in the fused MoE path.

- It normalizes MXFP8 activation scales to the packed 3D layout expected
by A5 kernels, including both precomputed dynamic_scale inputs and gmm1
output scales before they are consumed by downstream grouped matmul ops.
- It also refines the MXFP8 force load-balancing path in profiling runs.
- This PR also enables npu_gating_top_k from torch_npu instead of custom
op when running ascend950 chip.
### Does this PR introduce _any_ user-facing change?
No.

### How was this patch tested?
CI and E2E serving tests on Ascend950DT passed.

---------

Signed-off-by: linfeng-yuan <1102311262@qq.com>

vllm_ascend/ops/fused_moe/moe_mlp.py

@@ -128,7 +128,9 @@ def quant_apply_mlp(
         quantized_hidden_states = None
     else:
         unquantized_hidden_states = None
-        pertoken_scale = dynamic_scale
+        pertoken_scale = (
+            DeviceOperator.maybe_normalize_mxfp_scale_layout(dynamic_scale) if use_mxfp_quant else dynamic_scale
+        )
         quantized_hidden_states = hidden_states
 
     bias1, bias2 = None, None