Optimize the concat and split kernel for specical cases when the number of inputs/outputs is 2 (#17415)

* Optimize the concat and split kernel for special cases that the number of inputs/outputs is 2.
test=develop

* Refine codes.
test=develop

* Correct the condition.
test=develop

* Move the define of tmp_data outside the if statement.

* Print the cudnn minor version.
test=develop

* Fix the case when in_num/o_num is 1 in concat/split op.
test=develop

* Remove const_cast.
test=develop

cmake/cudnn.cmake

@@ -96,7 +96,7 @@ if(CUDNN_FOUND)
         endif()
 
         message(STATUS "Current cuDNN header is ${CUDNN_INCLUDE_DIR}/cudnn.h. "
-            "Current cuDNN version is v${CUDNN_MAJOR_VERSION}. ")
+            "Current cuDNN version is v${CUDNN_MAJOR_VERSION}.${CUDNN_MINOR_VERSION}. ")
 
     endif()
 endif()