STA OBSS: Update secondary channel info after CSA

STA OBSS: Update secondary channel info after CSA

Field wpa_s->sme.ht_sec_chan keeps secondary channel for the 40 MHz
band. This field is used to prepare a list of channels for the STA OBSS
scan. Initially, the secondary channel is set to HT_SEC_CHAN_UNKNOWN.
Later on, in function wpa_obss_scan_freq_list() it is obtained from the
current BSS HT operation IE. However, the secondary channel information
is not updated after channel switch, which may lead to an incorrect list
of channels prepared for the STA OBSS scan.

Update ht_sec_chan according to the channel switch event data to fix
this.

Signed-off-by: Sergey Matyukevich <sergey.matyukevich.os@quantenna.com>