kernel: Using boolean constants instead of 0 or 1

MISRA C requires that every controlling expression of and if or while
statement have a boolean type.

Signed-off-by: Flavio Ceolin <flavio.ceolin@intel.com>
diff --git a/kernel/include/kernel_internal.h b/kernel/include/kernel_internal.h
index 9b15c59..9b203fc 100644
--- a/kernel/include/kernel_internal.h
+++ b/kernel/include/kernel_internal.h
@@ -15,6 +15,7 @@
 #define ZEPHYR_KERNEL_INCLUDE_KERNEL_INTERNAL_H_
 
 #include <kernel.h>
+#include <stdbool.h>
 
 #ifndef _ASMLANGUAGE
 
@@ -198,7 +199,7 @@
 #else
 #define _thread_monitor_exit(thread) \
 	do {/* nothing */    \
-	} while (0)
+	} while (false)
 #endif /* CONFIG_THREAD_MONITOR */
 
 extern void smp_init(void);