[rocm-libraries] ROCm/rocm-libraries#6873 (commit b61b3fb)

[CK] add swiglustep_and_mul activation to gridwise_moe_gemm (#6873)

Title：
feat(composablekernel): add swiglustep_and_mul activation to
gridwise_moe_gemm

  Description：
  ## Motivation

Step-3.5-Flash uses a clamped SwiGLU activation (`swiglu_limits[43]=7`,
  `swiglu_limits[44]=7`) for layers 43 and 44. Without this kernel path,
  those layers produce BOS token spam because unclamped gate/up values
  accumulate floating-point noise over 200+ decode steps, degrading
  output quality (cosine similarity drops from 0.999989 to ~0.998982).

  ## Changes

  Add `swiglustep_and_mul` as a new `Activation` enum branch in
  `gridwise_moe_gemm.hpp`, covering all 4 code paths:
  - Quantized (A×B scale) + IsInputGemm=true
  - Quantized (A×B scale) + IsInputGemm=false
  - Non-quantized + IsInputGemm=true
  - Non-quantized + IsInputGemm=false

  The activation computes:
  gate = silu(gate)
  gate = clamp(gate, max=7.0f)
  up   = clamp(up,   min=-7.0f, max=7.0f)
  output = gate * up

Also handles the `MulRoutedWeight` case (topk weight multiplication) and
  `pk_i4_t` weight scaling (×16 dequant factor).

  ## Verification

  - Tested on gfx950 (MI350X, 8×GPU)
- cosine similarity for layers 43/44: **0.999989** (vs 0.998982 before
fix)
  - End-to-end Step-3.5-Flash inference: no BOS spam, output coherent
  - BF16 tp=2/tp=4 and FP8 tp=2/tp=4 all verified PASS
- [x] Look over the contributing guidelines at
https://github.com/ROCm/ROCm/blob/develop/CONTRIBUTING.md#pull-requests.