[rocm-libraries] ROCm/rocm-libraries#5504 (commit 47f86c7)

[CK Tile] Add sink token gradient support in FMHA backward
 pass (#5504)

## Motivation

Adds sink token support to the FMHA backward kernel (dot_do_o pipeline):

## Technical Details

- Extend BlockFmhaBwdOGradDotOPipelineProblem with LSEDataType
- Add sink_ptr/d_sink_ptr/lse_ptr/nhead to FmhaBwdOGradDotOCommonKargs
- Compute per-head sink gradient via atomic accumulation in the pipeline
- Update example runner with reference validation for sink gradient

## Test Plan

Add new test case

## Test Result

WIP

## Submission Checklist

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

example/ck_tile/01_fmha/example_fmha_bwd.cpp

@@ -87,6 +87,7 @@ auto create_args(int argc, char* argv[])
                 "0",
                 "if set to 1 will use multi-buffer reduction strategy for dq, atomic operation "
                 "will not be used")
+        .insert("sink_grad", "0", "if set to 1, compute and validate sink token gradient")
         .insert("json", "0", "0: No Json, 1: Dump Results in Json format")
         .insert("jsonfile", "fmha_bwd.json", "json file name to dump results");
 
@@ -122,6 +123,7 @@ auto run(const ck_tile::ArgParser& arg_parser)
     bool deterministic       = arg_parser.get_bool("deterministic");
     std::string init_method  = arg_parser.get_str("init");
     uint32_t seed            = arg_parser.get_uint32("seed");
+    bool sink_grad           = arg_parser.get_bool("sink_grad");
 
     ck_tile::stream_config stream_config{nullptr,
                                          true,
@@ -154,6 +156,7 @@ auto run(const ck_tile::ArgParser& arg_parser)
                                         drop_offset,
                                         drop_prefs,
                                         mask_str,
+                                        sink_grad,
                                         deterministic,
                                         init_method,
                                         seed,