AHCI: Make distinct names for ports in /proc/interrupts

Currently all interrupts assigned to AHCI ports show up in
'/proc/interrupts' as 'ahci'. This fix adds port numbers as
suffixes and hence makes the descriptions distinct.

Reported-by: Jan Beulich <JBeulich@suse.com>
Signed-off-by: Alexander Gordeev <agordeev@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/drivers/ata/libahci.c b/drivers/ata/libahci.c
index 34c8216..3797a7b 100644
--- a/drivers/ata/libahci.c
+++ b/drivers/ata/libahci.c
@@ -2234,6 +2234,16 @@
 	if (!pp)
 		return -ENOMEM;
 
+	if (ap->host->n_ports > 1) {
+		pp->irq_desc = devm_kzalloc(dev, 8, GFP_KERNEL);
+		if (!pp->irq_desc) {
+			devm_kfree(dev, pp);
+			return -ENOMEM;
+		}
+		snprintf(pp->irq_desc, 8,
+			 "%s%d", dev_driver_string(dev), ap->port_no);
+	}
+
 	/* check FBS capability */
 	if ((hpriv->cap & HOST_CAP_FBS) && sata_pmp_supported(ap)) {
 		void __iomem *port_mmio = ahci_port_base(ap);