[S390] zcrypt: fix Kconfig dependencies

warning: (ZCRYPT && CRYPTO && CRYPTO_HW && S390 && ZCRYPT=y) selects
ZCRYPT_MONOLITHIC which has unmet direct dependencies (ZCRYPT=m)

ZCRYPT_MONOLITHIC should not depend on ZCRYPT="m" when it gets
selected if ZCRYPT="y".

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>