[S390] cio long busy in read configuration data.

Trying to set a DASD root device online can fail under some circumstances
with the message "Read configuration data returned error -5". The cause
is that read configuration data incorrectly aborts with -EIO when it
encounters a temporary busy condition at a storage server.
Perform retry when encountering temporary busy conditions.

Signed-off-by: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>