btrfs: remove duplicate btrfs_clear_buffer_dirty() prototype from disk-io.h

The prototype for btrfs_clear_buffer_dirty() is declared in both disk-io.h
and extent_io.h, but the function is defined at extent_io.c. So remove the
prototype declaration from disk-io.h.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/disk-io.h

@@ -37,8 +37,6 @@ struct extent_buffer *btrfs_find_create_tree_block(
 						struct btrfs_fs_info *fs_info,
 						u64 bytenr, u64 owner_root,
 						int level);
-void btrfs_clear_buffer_dirty(struct btrfs_trans_handle *trans,
-			      struct extent_buffer *buf);
 void btrfs_clear_oneshot_options(struct btrfs_fs_info *fs_info);
 int btrfs_start_pre_rw_mount(struct btrfs_fs_info *fs_info);
 int btrfs_check_super_csum(struct btrfs_fs_info *fs_info,