wl12xx: AP mode - changes in TX path

When in AP mode set appropriate HLID and rate policy for each skb.
Respond to supported-rates related changes in op_tx only when acting
as STA.

Signed-off-by: Arik Nemtsov <arik@wizery.com>
Reviewed-by: Luciano Coelho <coelho@ti.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>