[rocm-libraries] ROCm/rocm-libraries#8241 (commit cd183df)

[CK] increase time limit for fmha_bwd tests to prevent
 timeouts (#8241)

## Motivation

Observed a CI failure due to fmha_bwd test timeout which never happened
before. Going to increase the time limit for the test to prevent any
further CI failures.

## Technical Details

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## 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.