Get rid of duplicated code by introducing some helpers to allocate
and free qdio queues used by qeth for its input and completion queue.

No functional change.
Reviewed-by: NUrsula Braun <ursula.braun@de.ibm.com>
Signed-off-by: NSebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>