wl18xx: move to new firmware (wl18xx-fw-3.bin)

Bump the min wl18xx fw version to 8.8.0.0.13

This fw is not backward compatible with older
firmware (due to api changes), so use bump
the firmware name as well.

Some modifications were done to the driver-fw api
in order to support multiple APs.

Additionally, some of the consts (such as max stations,
max links and max RX BA sessions) were changed.

Signed-off-by: Arik Nemtsov <arik@wizery.com>
Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>