qeth: avoid qeth recovery problems

Do not touch IFF_UP flag during qeth recovery, but invoke dev_close()
in case of failing recovery.
Cancel outstanding control commands in case of Data Checks or
Channel Checks.
Do not invoke qeth_l2_del_all_mc() in case of a hard stop to speed up
removal of qeth devices.

Signed-off-by: Ursula Braun <ursula.braun@de.ibm.com>
Signed-off-by: Frank Blaschka <frank.blaschka@de.ibm.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>