with flash gt 11.2 (#51307)

cmake/third_party.cmake

@@ -531,6 +531,8 @@ if(WITH_GPU
     include(external/cutlass) # download, build, install cusparselt
     list(APPEND third_party_deps extern_cutlass)
     set(WITH_CUTLASS ON)
+  endif()
+  if(${CMAKE_CUDA_COMPILER_VERSION} GREATER_EQUAL 11.2)
     include(external/flashattn)
     list(APPEND third_party_deps extern_flashattn)
     set(WITH_FLASHATTN ON)