fs: btrfs: Crossport btrfs_read_sys_array() and btrfs_read_chunk_tree()

These two functions play a big role in btrfs bootstrap.

The following function is removed:
- Seed device support

Although in theory we can still support multiple devices, we don't have
a facility in U-Boot to do device scan without opening them.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Marek BehĂșn <marek.behun@nic.cz>
diff --git a/fs/btrfs/chunk-map.c b/fs/btrfs/chunk-map.c
index 8e3d13c..bff83e4 100644
--- a/fs/btrfs/chunk-map.c
+++ b/fs/btrfs/chunk-map.c
@@ -142,7 +142,7 @@
 	return 0;
 }
 
-int btrfs_read_chunk_tree(void)
+int __btrfs_read_chunk_tree(void)
 {
 	struct __btrfs_path path;
 	struct btrfs_key key, *found_key;