kfdtest: Clean up comments

Consolidate style (use /* */ for multi-line), fix typos,
use dword instad of DWORD/DWord

Change-Id: I620e45c1687550db41127e45641b7d79d28223a1

tests/kfdtest/src/KFDGraphicsInterop.cpp

@@ -83,8 +83,9 @@ TEST_F(KFDGraphicsInterop, RegisterGraphicsHandle) {
     ASSERT_SUCCESS(hsaKmtRegisterGraphicsHandleToNodes(dmabufFd, &info,
                                                        1, nodes));
 
-    // DMA buffer handle and GEM handle are no longer needed, KFD
-    // should have taken a reference to the BO
+    /* DMA buffer handle and GEM handle are no longer needed, KFD
+     * should have taken a reference to the BO
+     */
     ASSERT_EQ(0, close(dmabufFd));
     ASSERT_EQ(0, amdgpu_bo_free(handle));