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>

include/sandboxfs.h

@@ -18,7 +18,7 @@
 #ifndef __SANDBOX_FS__
 #define __SANDBOX_FS__
 
-int sandbox_fs_set_blk_dev(block_dev_desc_t *rbdd, disk_partition_t *info);
+int sandbox_fs_set_blk_dev(struct blk_desc *rbdd, disk_partition_t *info);
 
 int sandbox_fs_read_at(const char *filename, loff_t pos, void *buffer,
 		       loff_t maxsize, loff_t *actread);