kfdtest: Use GetSystemTickCountInMicroSec() as much as possible

GetSystemTickCountInMicroSec() wraps the function gettimeofday().

Change-Id: I7b767a6efdd1db491fc8113313945b578ac69382
Signed-off-by: Yong Zhao <Yong.Zhao@amd.com>

tests/kfdtest/src/KFDTestUtil.hpp

@@ -56,6 +56,8 @@ void GetSdmaInfo(const HsaNodeProperties *props,
                  unsigned int *p_num_sdma_xgmi_engines,
                  unsigned int *p_num_sdma_queues_per_engine);
 
+HSAuint64 GetSystemTickCountInMicroSec();
+
 class HsaMemoryBuffer {
  public:
     static const HsaMemoryBuffer Null;