Fix 40 MHz channel bringup with ACS on the 6 GHz band

Fix 40 MHz channel bringup with ACS on the 6 GHz band

When AP is brought up in HE40/EHT40 with ACS, the AP comes up with 20
MHz bandwidth. It is expected to come up with 40 MHz bandwidth.

conf->secondary_channel does not hold the correct value and it leads to
choosing 20 MHz in hostapd_set_freq_params(). conf->secondary_channel is
filled using the hostapd config he_oper_centr_freq_seg0_idx. When AP is
configured to use ACS, the hostapd config he_oper_centr_freq_seg0_idx is
not valid as the channel is not known during bring up. So using the
config he_oper_centr_freq_seg0_idx to fill the conf->secondary_channel
does not work with ACS.

Use op_class to determine the bandwidth and based on the bandwidth fill
the conf->secondary_channel to address this ACS case.

Signed-off-by: Hari Chandrakanthan <quic_haric@quicinc.com>