ath11k: set psc channel flag when sending channel list to firmware.

If 6 ghz channel is a Preferred Scanning Channel(PSC), mark
the channel flag accordingly when updating channel list to firmware.
This will be used when making scanning decision in 6GHz channels.

Signed-off-by: Pradeep Kumar Chitrapu <pradeepc@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200603001724.12161-6-pradeepc@codeaurora.org