Bluetooth: btmtksdio: Prevent enabling interrupts after IRQ handler removal

Ensure interrupts are not re-enabled when the IRQ handler has already been
removed. This prevents unexpected IRQ handler execution due to stale or
unhandled interrupts.

Modify btmtksdio_txrx_work to check if bdev->func->irq_handler exists
before calling sdio_writel to enable interrupts.

Co-developed-by: Pedro Tsai <pedro.tsai@mediatek.com>
Signed-off-by: Pedro Tsai <pedro.tsai@mediatek.com>
Co-developed-by: Felix Freimann <felix.freimann@mediatek.com>
Signed-off-by: Felix Freimann <felix.freimann@mediatek.com>
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

Author: moore-bros

drivers/bluetooth/btmtksdio.c

@@ -610,7 +610,8 @@ static void btmtksdio_txrx_work(struct work_struct *work)
 	} while (int_status || time_is_before_jiffies(txrx_timeout));
 
 	/* Enable interrupt */
-	sdio_writel(bdev->func, C_INT_EN_SET, MTK_REG_CHLPCR, NULL);
+	if (bdev->func->irq_handler)
+		sdio_writel(bdev->func, C_INT_EN_SET, MTK_REG_CHLPCR, NULL);
 
 	sdio_release_host(bdev->func);