tests/kernel: Fix code compliance issues

Fix issues detected by checkpatch

Signed-off-by: Alberto Escolar Piedras <alberto.escolar.piedras@nordicsemi.no>

Author: aescolar

tests/kernel/common/src/clock.c

@@ -240,5 +240,5 @@ ZTEST(clock, test_ms_time_duration)
  * @}
  */
 
- extern void *common_setup(void);
- ZTEST_SUITE(clock, NULL, common_setup, NULL, NULL, NULL);
+extern void *common_setup(void);
+ZTEST_SUITE(clock, NULL, common_setup, NULL, NULL, NULL);

tests/kernel/common/src/constructor.c

@@ -59,5 +59,5 @@ ZTEST(constructor, test_constructor)
  * @}
  */
 
- extern void *common_setup(void);
- ZTEST_SUITE(constructor, NULL, common_setup, NULL, NULL, NULL);
+extern void *common_setup(void);
+ZTEST_SUITE(constructor, NULL, common_setup, NULL, NULL, NULL);

tests/kernel/events/event_api/src/test_event_apis.c

@@ -47,9 +47,9 @@ static void entry_extra2(void *p1, void *p2, void *p3)
 	k_event_post(&test_event, events);
 }
 /**
-* @ingroup kernel_event_tests
-* @{
-*/
+ * @ingroup kernel_event_tests
+ * @{
+ */
 
 /**
  * Test the k_event_init() API.