s390/qeth: Fix initialization of vnicc cmd masks during set online

Without this patch, a command bit in the supported commands mask is only
ever set to unsupported during set online. If a command is ever marked as
unsupported (e.g. because of error during qeth_l2_vnicc_query_cmds),
subsequent successful initialization (offline/online) would not bring it
back.

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: Jakub Kicinski <jakub.kicinski@netronome.com>