[NET]: Change type of owner in sock_lock_t to int, rename

The type of owner in sock_lock_t is currently (struct sock_iocb *),
presumably for historical reasons.  It is never used as this type, only
tested as NULL or set to (void *)1.  For clarity, this changes it to type
int, and renames to owned, to avoid any possible type casting errors.

Signed-off-by: John Heffner <jheffner@psc.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>