CAPI: Drop obsolete nccip from capiminor struct

The nccip in capiminor used to serve as an indicator that the NCCI was
close. But we don't need this, we issue a hangup on capincci_free_minor.
So drop this legacy.

Signed-off-by: Jan Kiszka <jan.kiszka@web.de>
Signed-off-by: David S. Miller <davem@davemloft.net>