s390/sclp: get rid of common response code handling

Get rid of common response code handling. Each command requires its
own response code handling anyway. Also the retry in case of -EBUSY
does not work and can be simply removed.

Reviewed-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>