wcn36xx: Fix reported 802.11n rx_highest rate wcn3660/wcn3680

Qualcomm's document "80-WL007-1 Rev. J" states that the highest rx rate for
the WCN3660 and WCN3680 on MCS 7 is 150 Mbps not the 72 Mbps stated here.

This patch fixes the data-rate declared in the 5GHz table.

Fixes: 8e84c258 ("wcn36xx: mac80211 driver for Qualcomm WCN3660/WCN3680
hardware")

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>