sched/wdog: Faster wdog deleting.

This commit reduced 1 write operation for wdog deleting and decoupled
the WDOG_ISACTIVE with the list implementation.

Signed-off-by: ouyangxiangzhen <ouyangxiangzhen@xiaomi.com>

include/nuttx/list.h

@@ -138,20 +138,27 @@
     } \
   while (0)
 
-#define list_delete(item) \
+#define list_delete_fast(item) \
   do \
     { \
       FAR struct list_node *__item = (item); \
       __item->next->prev = __item->prev; \
       __item->prev->next = __item->next; \
-      __item->prev = __item->next = NULL; \
+    } \
+  while (0)
+
+#define list_delete(item) \
+  do \
+    { \
+      list_delete_fast(item); \
+      list_clear_node(item); \
     } \
   while (0)
 
 #define list_delete_init(item) \
   do \
     { \
-      list_delete(item); \
+      list_delete_fast(item); \
       list_initialize(item); \
     } \
   while (0)

include/nuttx/wdog.h

@@ -39,7 +39,7 @@
  * Pre-processor Definitions
  ****************************************************************************/
 
-#define WDOG_ISACTIVE(w)   (list_in_list(&((w)->node)))
+#define WDOG_ISACTIVE(w)   ((w)->func != NULL)
 
 /* The maximum delay tick are supposed to be CLOCK_MAX >> 1.
  * However, if there are expired wdog timers in the wdog queue,