Add reference counting for creating devices

[planetA]

Adding and deleting devices must participate in reference counting for the module usage. Opening and closing device must count for the device usage.

linux/drivers/infiniband/sw/ovey/ovey.c

Line 296 in bec236a

int ovey_gnl_new_device(struct sk_buff *skb, struct genl_info *info)

rmmod ovey must delete existing devices. If some device is open, the driver must not be removed.