wcn36xx: Differentiate wcn3660 from wcn3620

The spread of capability between the three WiFi silicon parts wcn36xx
supports is:

wcn3620 - 802.11 a/b/g
wcn3660 - 802.11 a/b/g/n
wcn3680 - 802.11 a/b/g/n/ac

We currently treat wcn3660 as wcn3620 thus limiting it to 2GHz channels.
Fix this regression by ensuring we differentiate between all three parts.

Fixes: 8490987b

 ("wcn36xx: Hook and identify RF_IRIS_WCN3680")
Cc: stable@vger.kernel.org
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Reviewed-by: Loic Poulain <loic.poulain@linaro.org>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20220125004046.4058284-1-bryan.odonoghue@linaro.org