[rocm-libraries] ROCm/rocm-libraries#5612 (commit 38c9498)

[CK]fix: remove redundant structured sparsity check in run_gemm_example.inc (#5612)

## Motivation

This issue if found via
https://github.com/ROCm/rocm-libraries/pull/4302#discussion_r2958603418
and is introduced via https://github.com/ROCm/rocm-libraries/pull/5323.

## Technical Details

The outer `if` and inner `if constexpr` both checked
GemmConfig::UseStructuredSparsity. Merged into a single `if constexpr`
since both preshuffle and UseStructuredSparsity are compile-time
constants.

## Test Plan

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## Test Result

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## Submission Checklist

- [ ] Look over the contributing guidelines at
https://github.com/ROCm/ROCm/blob/develop/CONTRIBUTING.md#pull-requests.