s390/qeth: clarify naming for some QDIO helpers

The naming of several QDIO helpers doesn't match their actual
functionality, or the structures they operate on. Clean this up.

s/qeth_alloc_qdio_buffers/qeth_alloc_qdio_queues
s/qeth_free_qdio_buffers/qeth_free_qdio_queues
s/qeth_alloc_qdio_out_buf/qeth_alloc_output_queue
s/qeth_clear_outq_buffers/qeth_drain_output_queue
s/qeth_clear_qdio_buffers/qeth_drain_output_queues

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>