qtnfmac: make "Channel change" event report full channel info

Specifically, it has to report center frequency, secondary center
frequency (for 80+80) and BW.
Introduce channel definition structure to qlink and modify channel
change event processing function accordingly.

Signed-off-by: Igor Mitsyanko <igor.mitsyanko.os@quantenna.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>