dm: Drop the block_dev_desc_t typedef

Use 'struct' instead of a typdef. Also since 'struct block_dev_desc' is long
and causes 80-column violations, rename it to struct blk_desc.

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/board/cm5200/fwupdate.c b/board/cm5200/fwupdate.c
index 2b92362..d5064c1 100644
--- a/board/cm5200/fwupdate.c
+++ b/board/cm5200/fwupdate.c
@@ -81,7 +81,7 @@
 	char dev[7];
 	char addr_str[16];
 	char * const argv[6] = { "fatload", "usb", dev, addr_str, nxri, NULL };
-	block_dev_desc_t *stor_dev = NULL;
+	struct blk_desc *stor_dev = NULL;
 	cmd_tbl_t *bcmd;
 
 	/* Get name of firmware directory */