dm: blk: Use uclass_find_first/next_device() in blk_first/next_device()

This patch changes the calls to uclass_first/next_device() in blk_first/
next_device() to use uclass_find_first/next_device() instead. These functions
don't prepare the devices, which is correct in this case.

With this patch applied, the "usb storage" command now works again as
expected:

=> usb storage
  Device 0: Vendor: SanDisk Rev: 1.00 Prod: Ultra
  Type: Removable Hard Disk
  Capacity: 58656.0 MB = 57.2 GB (120127488 x 512)

Without this patch, it used to generate this buggy output:

=> usb storage
Card did not respond to voltage select!
mmc_init: -95, time 26
No storage devices, perhaps not 'usb start'ed..?

Signed-off-by: Stefan Roese <sr@denx.de>
Suggested-by: Simon Glass <sjg@chromium.org>
Cc: Simon Glass <sjg@chromium.org>
Cc: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

drivers/block/blk-uclass.c

@@ -10,6 +10,7 @@
 #include <dm.h>
 #include <dm/device-internal.h>
 #include <dm/lists.h>
+#include <dm/uclass-internal.h>
 
 static const char *if_typename_str[IF_TYPE_COUNT] = {
 	[IF_TYPE_IDE]		= "ide",
@@ -331,7 +332,7 @@ int blk_first_device(int if_type, struct udevice **devp)
 	struct blk_desc *desc;
 	int ret;
 
-	ret = uclass_first_device(UCLASS_BLK, devp);
+	ret = uclass_find_first_device(UCLASS_BLK, devp);
 	if (ret)
 		return ret;
 	if (!*devp)
@@ -340,7 +341,7 @@ int blk_first_device(int if_type, struct udevice **devp)
 		desc = dev_get_uclass_platdata(*devp);
 		if (desc->if_type == if_type)
 			return 0;
-		ret = uclass_next_device(devp);
+		ret = uclass_find_next_device(devp);
 		if (ret)
 			return ret;
 	} while (*devp);
@@ -356,7 +357,7 @@ int blk_next_device(struct udevice **devp)
 	desc = dev_get_uclass_platdata(*devp);
 	if_type = desc->if_type;
 	do {
-		ret = uclass_next_device(devp);
+		ret = uclass_find_next_device(devp);
 		if (ret)
 			return ret;
 		if (!*devp)