iio: xilinx-xadc: Remove `irq` field from state struct

Since commit 2a9685d1a3b7 ("iio: adc: xilinx: use more devres helpers and
remove remove()") the `irq` field from XADC driver state struct is only
used in the `probe()` function.

Use the local `irq` variable throughout the `probe()` function and remove
the now unused field from the state struct.

Signed-off-by: Lars-Peter Clausen <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/adc/xilinx-xadc-core.c

···
 
 	xadc = iio_priv(indio_dev);
 	xadc->ops = id->data;
-	xadc->irq = irq;
 	init_completion(&xadc->completion);
 	mutex_init(&xadc->mutex);
 	spin_lock_init(&xadc->lock);
···
 		}
 	}
 
-	ret = devm_request_irq(dev, xadc->irq, xadc->ops->interrupt_handler, 0,
+	ret = devm_request_irq(dev, irq, xadc->ops->interrupt_handler, 0,
 			       dev_name(dev), indio_dev);
 	if (ret)
 		return ret;
···
 	if (ret)
 		return ret;
 
-	ret = xadc->ops->setup(pdev, indio_dev, xadc->irq);
+	ret = xadc->ops->setup(pdev, indio_dev, irq);
 	if (ret)
 		return ret;
 

drivers/iio/adc/xilinx-xadc.h

···
 	spinlock_t lock;
 
 	struct completion completion;
-	int irq;
 };
 
 enum xadc_type {