fix comments

Author: wentaoyu

cmake/external/flashattn.cmake

@@ -20,7 +20,7 @@ set(FLASHATTN_PREFIX_DIR ${THIRD_PARTY_PATH}/flashattn)
 set(FLASHATTN_SOURCE_SUBDIR csrc)
 set(FLASHATTN_INSTALL_DIR ${THIRD_PARTY_PATH}/install/flashattn)
 set(SOURCE_DIR ${PADDLE_SOURCE_DIR}/third_party/flashattn)
-set(FLASHATTN_TAG b5bdb79d5e1f2f88b1ef62e86899a14f82fa079a)
+set(FLASHATTN_TAG 18106c1ba0ccee81b97ca947397c08a141815a47)
 
 set(FLASHATTN_INCLUDE_DIR
     "${FLASHATTN_INSTALL_DIR}/include"

paddle/phi/kernels/gpu/flash_attn_grad_kernel.cu

@@ -23,10 +23,6 @@
 
 PD_DECLARE_bool(cudnn_deterministic);
 
-#ifdef PADDLE_WITH_FLASHATTN
-#include "paddle/phi/backends/dynload/flashattn.h"
-#endif
-
 namespace phi {
 
 int get_num_split() {