crypto: omap-aes - fix error return code in omap_aes_probe()

Fix to return error code -ENOMEM from the crypto_engine_alloc_init()
error handling case instead of 0, as done elsewhere in this function.

Fixes: 0529900a

 ("crypto: omap-aes - Support crypto engine framework")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>