libinput: Use #pragma once instead of explicit define guards

The #pragma once directive is commonly used by modern cpp code, and
support for its use in Andorid is proposed in go/droidcppstyle.

Bug: 245989146
Test: Build, Presubmit
Change-Id: Ib7852f1a343864dff46e7bc616d707bc7d5bf512
diff --git a/include/input/TouchVideoFrame.h b/include/input/TouchVideoFrame.h
index eda628e..a616a95 100644
--- a/include/input/TouchVideoFrame.h
+++ b/include/input/TouchVideoFrame.h
@@ -14,8 +14,7 @@
  * limitations under the License.
  */
 
-#ifndef _LIBINPUT_TOUCHVIDEOFRAME_H
-#define _LIBINPUT_TOUCHVIDEOFRAME_H
+#pragma once
 
 #include <stdint.h>
 #include <sys/time.h>
@@ -75,5 +74,3 @@
 };
 
 } // namespace android
-
-#endif // _LIBINPUT_TOUCHVIDEOFRAME_H