s390/appldata: change return value of appldata_asm

Change return value of appldata_asm() to -EOPNOTSUPP in case of an
error. The return value was only used internally and not passed to
user space.

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