aon_counter test: fix misspelling in the header include guard

The include guard has a misspelling.

Jira: ZEP-1746

Change-Id: I4d8000ef5c8e037f80acbf2491d0b9466670816a
Signed-off-by: Kuo-Lang Tseng <[email protected]>
(cherry picked from commit 4533734)

Author: kltseng

tests/drivers/aon_counter/aon_api/src/test_aon.h

@@ -11,7 +11,7 @@
  * Header file for AON cases
  */
 
-#ifndef __TEST_AON_H_
+#ifndef __TEST_AON_H__
 #define __TEST_AON_H__
 
 #include <counter.h>