[S390] 3215: Handle special console device.

The early console device is special as it already has all needed data
set and raw3215[0] allocated from con3215_init(). Therefore, it needs
special treatment in the probe function so it can be matched with the
3215 driver which is already owning it.

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