s390/sclp: don't add new lines to each printed string

The early vt220 sclp printk code added an extra new line to each
printed multi-line text. If used for the early sclp console this will
lead to numerous extra new lines. Therefore get rid of this semantic
and require that each to be printed string contains a line feed
character if a new line is wanted.

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>