[S390] cio: Remove check for ssd in chpids_show().

Since ssd_info is now available before the subchannel is registered,
we don't need to check whether it is available.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>