qeth: allow change of blkt default values

There exist qeth sysfs blkt attributes to change the default blkt
values. But blkt changes are reset during online setting due to a 2nd
invocation of qeth_determine_capabilites(). This patch makes sure
blkt default values are configured during 1st run of
qeth_determine_capabilities() only. Thus blkt changes are kept
during online setting.

Signed-off-by: Ursula Braun <ursula.braun@de.ibm.com>
Reported-by: Horst Hartmann <horst.hartmann@de.ibm.com>
Signed-off-by: Frank Blaschka <frank.blaschka@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>