wifi: brcmsmac: remove unused data type

Remove unused 'struct gpioh_item'. It seems it was so since
commit 5b435de0 ("net: wireless: add brcm80211 drivers").
Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230719083232.158177-1-dmantipov@yandex.ru

drivers/net/wireless/broadcom/brcm80211/brcmsmac/aiutils.h

@@ -145,14 +145,6 @@ struct si_pub {
 
 struct pci_dev;
 
-struct gpioh_item {
-	void *arg;
-	bool level;
-	void (*handler) (u32 stat, void *arg);
-	u32 event;
-	struct gpioh_item *next;
-};
-
 /* misc si info needed by some of the routines */
 struct si_info {
 	struct si_pub pub;	/* back plane public state (must be first) */