ata: libata-sff: use *switch* statement in ata_sff_dev_classify()

In ata_sff_dev_classify(), replace a string of the *if* statements checking
the device's class with the *switch* statement that fits better here...

While at it, fix the multi-line comment style in the vicinity...
Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>

drivers/ata/libata-sff.c

@@ -1842,9 +1842,10 @@ unsigned int ata_sff_dev_classify(struct ata_device *dev, int present,
 
 	/* determine if device is ATA or ATAPI */
 	class = ata_port_classify(ap, &tf);
-
-	if (class == ATA_DEV_UNKNOWN) {
-		/* If the device failed diagnostic, it's likely to
+	switch (class) {
+	case ATA_DEV_UNKNOWN:
+		/*
+		 * If the device failed diagnostic, it's likely to
 		 * have reported incorrect device signature too.
 		 * Assume ATA device if the device seems present but
 		 * device signature is invalid with diagnostic
@@ -1854,10 +1855,12 @@ unsigned int ata_sff_dev_classify(struct ata_device *dev, int present,
 			class = ATA_DEV_ATA;
 		else
 			class = ATA_DEV_NONE;
-	} else if ((class == ATA_DEV_ATA) &&
-		   (ap->ops->sff_check_status(ap) == 0))
+		break;
+	case ATA_DEV_ATA:
+		if (ap->ops->sff_check_status(ap) == 0)
 			class = ATA_DEV_NONE;
-
+		break;
+	}
 	return class;
 }
 EXPORT_SYMBOL_GPL(ata_sff_dev_classify);