blk: Switch over to using uclass IDs

We currently have an if_type (interface type) and a uclass id. These are
closely related and we don't need to have both.

Drop the if_type values and use the uclass ones instead.

Maintain the existing, subtle, one-way conversion between UCLASS_USB and
UCLASS_MASS_STORAGE for now, and add a comment.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index 78d729d..99be5ae 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -456,7 +456,7 @@
 {
 	dev_desc->lba = 0;
 	dev_desc->blksz = 0;
-	dev_desc->if_type = IF_TYPE_SCSI;
+	dev_desc->if_type = UCLASS_SCSI;
 	dev_desc->devnum = devnum;
 	dev_desc->part_type = PART_TYPE_UNKNOWN;
 
@@ -574,8 +574,8 @@
 	* block devices created
 	*/
 	snprintf(str, sizeof(str), "id%dlun%d", id, lun);
-	ret = blk_create_devicef(dev, "scsi_blk", str, IF_TYPE_SCSI, -1,
-			bd.blksz, bd.lba, &bdev);
+	ret = blk_create_devicef(dev, "scsi_blk", str, UCLASS_SCSI, -1,
+				 bd.blksz, bd.lba, &bdev);
 	if (ret) {
 		debug("Can't create device\n");
 		return ret;
@@ -638,7 +638,7 @@
 	if (verbose)
 		printf("scanning bus for devices...\n");
 
-	blk_unbind_all(IF_TYPE_SCSI);
+	blk_unbind_all(UCLASS_SCSI);
 
 	ret = uclass_get(UCLASS_SCSI, &uc);
 	if (ret)
@@ -707,7 +707,7 @@
 #else
 U_BOOT_LEGACY_BLK(scsi) = {
 	.if_typename	= "scsi",
-	.if_type	= IF_TYPE_SCSI,
+	.if_type	= UCLASS_SCSI,
 	.max_devs	= SCSI_MAX_DEVICE,
 	.desc		= scsi_dev_desc,
 };