Add missing "select CRYPTO_DES". Fixes this:

ERROR: "des_ekey" [arch/s390/crypto/des_s390.ko] undefined!
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>