Revert "roll back splitkv"

This reverts commit 60113859.

include/ck_tile/ops/fmha/pipeline/block_fmha_fwd_splitkv_combine_pipeline.hpp

@@ -95,6 +95,8 @@ struct BlockFmhaFwdSplitKVCombinePipeline
             {
                 constexpr std::array occupancy{2, 2, 2, 2, 2, 1};
                 return occupancy[detail::log2<kMaxSplits>::value - 2];
+            } else if constexpr(kHeadDimV <= 512) {
+                return 1;
             }
         }
     }();

include/ck_tile/ops/fmha/pipeline/block_fmha_fwd_splitkv_pipeline_qr_ks_vs.hpp

@@ -96,6 +96,10 @@ struct BlockFmhaFwdSplitKVPipelineQRKSVS
             {
                 return 1;
             }
+            else if constexpr(kQKHeaddim <= 512) 
+            {
+                return 1;
+            }
         }
     }();