dm: block: Adjust device calls to go through helpers function

To ease conversion to driver model, add helper functions which deal with
calling each block device method. With driver model we can reimplement these
functions with the same arguments.

Use inline functions to avoid increasing code size on some boards.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Stephen Warren <swarren@nvidia.com>
diff --git a/common/fb_mmc.c b/common/fb_mmc.c
index da7949f..e3abcc8 100644
--- a/common/fb_mmc.c
+++ b/common/fb_mmc.c
@@ -6,6 +6,7 @@
 
 #include <config.h>
 #include <common.h>
+#include <blk.h>
 #include <errno.h>
 #include <fastboot.h>
 #include <fb_mmc.h>
@@ -58,7 +59,7 @@
 	struct blk_desc *dev_desc = sparse->dev_desc;
 	int ret;
 
-	ret = dev_desc->block_write(dev_desc, offset, size, data);
+	ret = blk_dwrite(dev_desc, offset, size, data);
 	if (!ret)
 		return -EIO;
 
@@ -84,7 +85,7 @@
 
 	puts("Flashing Raw Image\n");
 
-	blks = dev_desc->block_write(dev_desc, info->start, blkcnt, buffer);
+	blks = blk_dwrite(dev_desc, info->start, blkcnt, buffer);
 	if (blks != blkcnt) {
 		error("failed writing to device %d\n", dev_desc->devnum);
 		fastboot_fail(response_str, "failed writing to device");