The core function maintains address handlers by list. It is protected by
spinlock to insert and remove entry to the list.

This commit uses guard macro to maintain the spinlock.

Link: https://lore.kernel.org/r/20240805085408.251763-8-o-takashi@sakamocchi.jpSigned-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>