It's used only in inode.c so makes no sense to have it exported. Also
move the definition of btrfs_delalloc_work to inode.c since it's used
only this file.
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>