fs/affs: Fix resource leaks

fs/affs: Fix resource leaks

In commit 178ac5107389 (affs: Fix memory leaks), fixes were made to
grub_affs_iterate_dir() to prevent memory leaks from occurring after it
returns without freeing node. However, there were still some instances
where node was causing a memory leak when the function returns after
calling grub_affs_create_node(). In this function, new memory is
allocated to node but doesn't get freed until the hook() function is
called near the end. Before hook() is called, node should be freed in
grub_affs_create_node() before returning out of it.

Fixes: 178ac5107389 (affs: Fix memory leaks)
Fixes: CID 73759
Signed-off-by: Alec Brown <alec.r.brown@oracle.com>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>