net: ax88796c: use bit numbers insetad of bit masks

Change the values of EVENT_* constants from bit masks to bit numbers as
accepted by {clear,set,test}_bit() functions.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Łukasz Stelmach <l.stelmach@samsung.com>
Signed-off-by: David S. Miller <davem@davemloft.net>