wl12xx: use p2p rate index when the skb has the NO_CCK flag

If the skb contains the NO_CCK flag, use the p2p rate index
(which contains only the OFDM rates)

Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>