fs/eventfd/timerfd: update sem next to avoid busy loop

fix bug about busy loop

Signed-off-by: dongjiuzhu1 <dongjiuzhu1@xiaomi.com>

fs/vfs/fs_eventfd.c

@@ -255,6 +255,8 @@ static int eventfd_blocking_io(FAR struct eventfd_priv_s *dev,
                   cur_sem->next = sem->next;
                   break;
                 }
+
+              cur_sem = cur_sem->next;
             }
         }
 

fs/vfs/fs_timerfd.c

@@ -259,6 +259,8 @@ static int timerfd_blocking_io(FAR struct timerfd_priv_s *dev,
                   cur_sem->next = sem->next;
                   break;
                 }
+
+              cur_sem = cur_sem->next;
             }
         }
     }