s390/sclp: properly detect line mode console

To detect a line mode console we need a message event type
for the receive mask and a command event type for the send mask.
Checking for a MSG event in the sclp send mask was wrong and
might result in line mode consoles not being detected.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>