s390/qeth: vnicc Fix init to default

During vnicc_init wanted_char should be compared to cur_char and not
to QETH_VNICC_DEFAULT. Without this patch there is no way to enforce
the default values as desired values.

Note, that it is expected, that a card comes online with default values.
This patch was tested with private card firmware.

Fixes: caa1f0b1

 ("s390/qeth: add VNICC enable/disable support")
Signed-off-by: Alexandra Winter <wintera@linux.ibm.com>
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>