Staging: bcm: fix up network device reference counting

The way network devices are reference counted does not include poking
around in the reference count itself.  This breaks when the reference
count is changed to be a different type.  Fix the driver to do the
proper function calls instead.

Cc: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>