When loading encrypted-keys module, if the last check of
aes_get_sizes() in init_encrypted() fails, the driver just returns an
error without unregistering its key type. This results in the stale
entry in the list. In addition to memory leaks, this leads to a kernel
crash when registering a new key type later.
This patch fixes the problem by swapping the calls of aes_get_sizes()
and register_key_type(), and releasing resources properly at the error
paths.