wl12xx: correct fw_status structure for 8 sta support in AP-mode

Fix an erroneous labeling of array boundaries in the fw_status structure.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Arik Nemtsov <arik@wizery.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>