fs: btrfs: Rename struct btrfs_path to struct __btrfs_path

To avoid name conflicting between the extent buffer based btrfs_path
from btrfs-progs, rename struct btrfs_path to struct __btrfs_path.

Also rename btrfs_free_path() to __btrfs_free_path() to avoid conflicts.

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 2e5be65..8e3d13c 100644
--- a/fs/btrfs/chunk-map.c
+++ b/fs/btrfs/chunk-map.c
@@ -144,7 +144,7 @@
 
 int btrfs_read_chunk_tree(void)
 {
-	struct btrfs_path path;
+	struct __btrfs_path path;
 	struct btrfs_key key, *found_key;
 	struct btrfs_chunk *chunk;
 	int res = 0;
@@ -169,7 +169,7 @@
 		}
 	} while (!(res = btrfs_next_slot(&path)));
 
-	btrfs_free_path(&path);
+	__btrfs_free_path(&path);
 
 	if (res < 0)
 		return -1;