Unmap memory from GPU before free

Change-Id: Ic33b17cbaee5de7908d37527254f4f146e6b71e3
Signed-off-by: Oak Zeng <Oak.Zeng@amd.com>

tests/kfdtest/src/KFDMemoryTest.cpp

@@ -2165,6 +2165,7 @@ TEST_F(KFDMemoryTest, CacheInvalidateOnCPUWrite) {
     EXPECT_EQ(buffer[100], 0x5678);
 
     // Clean up
+    EXPECT_SUCCESS(hsaKmtUnmapMemoryToGPU(buffer));
     EXPECT_SUCCESS(hsaKmtFreeMemory(buffer, PAGE_SIZE));
     EXPECT_SUCCESS(queue.Destroy());