nl80211: use the 5Ghz band for dual bands radio

[rmelotte]

The Turris Omnia comes with a 2.4Ghz and a dual band radio by default.

Up to now we've only been taking into account the first band of each radio, which means we'll report two 2.4Ghz radios.

Supporting dual bands radio properly requires some refactoring, as the users of the RadioInfo struct would need to take the bands into account as well.

To allow the progress on the certification tests for the nl80211 bwl to continue, when a radio is a dual-band radio assume it's a 5Ghz radio only.

A Jira task has been added to properly support dual bands radios: https://jira.prplfoundation.org/browse/PPM-366

Signed-off-by: Raphaël Mélotte [email protected]