!7907 [MSLITE][Develop] fix fp16 memory leak

Merge pull request !7907 from sunsuodong/fix_memory_leak

mindspore/lite/src/runtime/kernel/arm/fp16/activation_fp16.cc

@@ -104,12 +104,6 @@ int ActivationFp16Run(void *cdata, int task_id) {
 
 int ActivationFp16CPUKernel::Run() {
   auto ret = MallocTmpBuffer();
-  if (ret != RET_OK) {
-    MS_LOG(ERROR) << "MallocTmpBuffer failed.";
-    return ret;
-  }
-
-  ret = MallocTmpBuffer();
   if (ret != RET_OK) {
     FreeTmpBuffer();
     return ret;