From: Frank Pavlic <pavlic@de.ibm.com>
- Clear read channel first prior to using ccw_device_set_offline.
- use QETH_DBF_TEXT instead of QETH_DBF_SPRINTF
- invoke qeth_halt_channel and qeth_clear_channel for all channels,
even if halt/clear for one of the channel fails.
- enable qeth_arp_query function for GuestLAN devices