virtio-ccw: Check the number of vqs in CCW_CMD_SET_IND

We cannot support more than 64 virtqueues with the 64 bits provided by
classic indicators. If a driver tries to setup classic indicators
(which it is free to do even for virtio-1 devices) for a device with
more than 64 virtqueues, we should reject the attempt so that the
driver does not end up with an unusable device.

This is in preparation for bumping the number of supported virtqueues
on the ccw transport.

Signed-off-by: Halil Pasic <pasic@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
