s390/cio: set device name as early as possible

Currently we set the device name at the time we call device_add after
we receive the interrupt for the first I/O. When something is not working
as expected during that first I/O (e.g. we don't receive an interrupt) we
print a message including the device name which has not yet been
initialized.

Set the device name after calling device_initialize (prior to starting
the first I/O) so that we have the name present if some unexpected error
occurs during that first I/O.

Reported-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Reported-by: Jason J. Herne <jjherne@linux.vnet.ibm.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>