mt76: Enable NL80211_EXT_FEATURE_CQM_RSSI_LIST

Enable the use of CQM_RSSI_LIST with mt76-devices. The change has been
tested with the mt7602, mt7603 and mt7621 PCI wifi-cards. I passed a
list of RSSI thresholds to the driver, and when disconnecting/connecting
the antenna(s) I got an event each time the RSSI went above/below a
threshold.

While I have not been able to test the change with any of the mt76
USB-devices (no access to a device), the RX RSSI management code is
shared between the two device types. Thus, CQM should also work with the
mt76 USB-devices.

Signed-off-by: Kristian Evensen <kristian.evensen@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>