lshal: use pragma once

For simplicity when adding new files.

Bug: N/A
Test: N/A
Change-Id: Ia66e5da5ff680b9287c4431799a935b58de02307
diff --git a/cmds/lshal/Timeout.h b/cmds/lshal/Timeout.h
index 46d8177..e8d22d9 100644
--- a/cmds/lshal/Timeout.h
+++ b/cmds/lshal/Timeout.h
@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#pragma once
+
 #include <condition_variable>
 #include <chrono>
 #include <functional>