pata_ipx4xx_cf: fix IRQ check

The driver's probe() method is written as if platform_get_irq() returns 0
on error, while actually it returns a negative error code (with all the
other values considered valid IRQs). Rewrite the driver's IRQ checking
code to pass the positive IRQ #s to ata_host_activate(), propagate errors
upstream, and treat IRQ0 as error, returning -EINVAL, as the libata code
treats 0 as an indication that polling should be used anyway...

Fixes: 0df0d0a0ea9f ("[libata] ARM: add ixp4xx PATA driver")
Signed-off-by: Sergey Shtylyov <[e-mail]>
Signed-off-by: Jens Axboe <[e-mail]>

drivers/ata/pata_ixp4xx_cf.c

···
 		return -ENOMEM;
 
 	irq = platform_get_irq(pdev, 0);
-	if (irq)
+	if (irq > 0)
 		irq_set_irq_type(irq, IRQ_TYPE_EDGE_RISING);
+	else if (irq < 0)
+		return irq;
+	else
+		return -EINVAL;
 
 	/* Setup expansion bus chip selects */
 	*data->cs0_cfg = data->cs0_bits;