[S390] qdio: fix init sequence

Reorder the initialization sequence of the qdio module to avoid
writing to an uninitialized debug feature entry. Also reorder
the exit function to restore a consistent cleanup path.

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