2022-11-23 firmware file changes break DBDC on mt7916

Hi there,

Recent (Nov 2022) changes to MT7916 firmware files, e.g. in linux-firmware commit cdf9499cf6706b73935a139bb5e76777a87674fe (link), break DBDC for me.

This manifests as being unable to transmit or receive from the 5/6GHz PHY on my AW7916-NPD (mt7916) through any manner. For example, stock hostapd is pointed at the card with this configuration:

config wifi-device 'radio1'     
        option type 'mac80211'
        option path 'ffe0a000.pcie/pcia000:02/a000:02:00.0/a000:03:00.0+1'
        option channel '36'                                               
        option band '5g'                                                  
        option htmode 'HE80'
        option disabled '0' 
                            
config wifi-iface 'default_radio1'
        option device 'radio1'    
        option network 'lan'      
        option mode 'ap'          
        option ssid 'AAAAAAAAAAAAAAAAA'
        option encryption 'psk2'       
        option key 'OpenWrtTest'   

... but despite not seeing any warnings when running wifi, no beacons are sent.

Tested on Extreme Networks AP3825i (mpc85xx) running OpenWrt current snapshot (r21523-4609228432).
Also tested using this board on OpenWrt 22.03.2, kmod-mt76 package version 5.10.146+2022-09-06-d7054646-4.

Reverting to firmware files from before linux-firmware's cdf9499cf6706b73935a139bb5e76777a87674fe fixes the issue.

Start by comparing the MT7916 firmware files before and after linux-firmware commit cdf9499cf6706b73935a139bb5e76777a87674fe, then reproduce the reported hostapd configuration on the AW7916-NPD or AP3825i. Check the OpenWrt snapshot and 22.03.2 cases described in the report. Done means DBDC works again, including transmission, reception, and beacons on the 5/6GHz PHY.