Removed unused variable "err" and directly return "0"

Reported by coccicheck -
./drivers/crypto/omap-aes.c:542:5-8: Unneeded variable: "err". Return "0" on line 551
./drivers/crypto/omap-des.c:530:5-8: Unneeded variable: "err". Return "0" on line 539
Signed-off-by: Rahul Pathak <rpathak@visteon.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>