[S390] cio: fix sanity checks in device_ops.

Some sanity checks in device_ops.c test the output of container_of
macros to be !NULL. Test the input parameters instead.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>