libata: clear ehi description after initial host report

ehi description field is used to carry LLD specific controller
description.  Sometimes, it's used without clearing before and LLD
description gets printed with exception information one more time.
Clear after printing.
Signed-off-by: NTejun Heo <htejun@gmail.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

drivers/ata/libata-core.c

@@ -6773,13 +6773,14 @@ int ata_host_register(struct ata_host *host, struct scsi_host_template *sht)
 		xfer_mask = ata_pack_xfermask(ap->pio_mask, ap->mwdma_mask,
 					      ap->udma_mask);
 
-		if (!ata_port_is_dummy(ap))
+		if (!ata_port_is_dummy(ap)) {
 			ata_port_printk(ap, KERN_INFO,
 					"%cATA max %s %s\n",
 					(ap->flags & ATA_FLAG_SATA) ? 'S' : 'P',
 					ata_mode_string(xfer_mask),
 					ap->link.eh_info.desc);
-		else
+			ata_ehi_clear_desc(&ap->link.eh_info);
+		} else
 			ata_port_printk(ap, KERN_INFO, "DUMMY\n");
 	}