btrfs: stop passing root argument to __btrfs_del_delalloc_inode()

There's no need to pass a root argument to __btrfs_del_delalloc_inode()
and btrfs_del_delalloc_inode(), we can just pass the inode since the root
is always the root associated to that inode. Some remove the root argument
from these functions.

Reviewed-by: Boris Burkov <boris@bur.io>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>