crypto: ixp4xx - Fix error handling path in 'aead_perform()'

In commit 0f987e25, the source processing has been moved in front of
the destination processing, but the error handling path has not been
modified accordingly.
Free resources in the correct order to avoid some leaks.

Cc: <stable@vger.kernel.org>
Fixes: 0f987e25 ("crypto: ixp4xx - Fix false lastlen uninitialised warning")
Reported-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>