s390/zcrypt: get rid of little/big endian handling

The zcrypt code contains a couple of functions which receive a
"big_endian" argument. All callers naturally pass "1" for big endian,
since s390 is big endian. Therefore get rid of this argument and also
get rid of the cpu_to_le()/cpu_to_be() calls.

This way we get rid of a couple of sparse warnings:

drivers/s390/crypto/zcrypt_cca_key.h:255:34:
 warning: incorrect type in assignment (different base types)
    expected unsigned short [unsigned] ulen
    got restricted __be16 [usertype] <noident>

Cc: Harald Freudenberger <freude@linux.vnet.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>