s390/qeth: improve QUERY CARD INFO processing

Move all the HW reply data parsing into qeth_query_card_info_cb(), and
use common ethtool enums for transporting the information back to the
caller.

Also only look at the .port_speed field when we couldn't determine the
speed from the .card_type field, and introduce some 'default' cases for
SPEED_UNKNOWN, PORT_OTHER and DUPLEX_UNKNOWN.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>