btrfs: move the csum helpers into ctree.h

These got moved because of copy+paste, but this code exists in ctree.c,
so move the declarations back into ctree.h.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/accessors.h

@@ -892,11 +892,6 @@ BTRFS_SETGET_STACK_FUNCS(super_magic, struct btrfs_super_block, magic, 64);
 BTRFS_SETGET_STACK_FUNCS(super_uuid_tree_generation, struct btrfs_super_block,
 			 uuid_tree_generation, 64);
 
-int btrfs_super_csum_size(const struct btrfs_super_block *s);
-const char *btrfs_super_csum_name(u16 csum_type);
-const char *btrfs_super_csum_driver(u16 csum_type);
-size_t __attribute_const__ btrfs_get_num_csums(void);
-
 /* struct btrfs_file_extent_item */
 BTRFS_SETGET_STACK_FUNCS(stack_file_extent_type, struct btrfs_file_extent_item,
 			 type, 8);

fs/btrfs/ctree.h

@@ -700,6 +700,11 @@ static inline bool btrfs_is_data_reloc_root(const struct btrfs_root *root)
 	return root->root_key.objectid == BTRFS_DATA_RELOC_TREE_OBJECTID;
 }
 
+int btrfs_super_csum_size(const struct btrfs_super_block *s);
+const char *btrfs_super_csum_name(u16 csum_type);
+const char *btrfs_super_csum_driver(u16 csum_type);
+size_t __attribute_const__ btrfs_get_num_csums(void);
+
 /*
  * We use page status Private2 to indicate there is an ordered extent with
  * unfinished IO.