hostapd: fix reload frequency change patch

hostapd: fix reload frequency change patch

When sta is configured, hostapd receives 'stop' and 'update' command from
wpa_supplicant. In the update command, hostapd gets sta parameters with
which it configures ap.

Problem is, with the default wireless configuration:
mode:11g freq:2.4GHz channel:1
If sta is connected to 5GHz network, then ap does not work. Ideally with
340-reload_freq_change.patch hostapd should reload the frequency changes
and start ap in 5GHz, but ap becomes invisible in the network.

This issue can be reproduced with following /etc/config/wireless:
config wifi-device  radio0
        option type     mac80211
        option channel  1
        option hwmode   11g
        option path     'virtual/uccp420/uccwlan'
        option htmode   'none'

config wifi-iface 'ap'
        option device 'radio0'
        option encryption 'none'
        option mode 'ap'
        option network 'ap'
        option ssid 'MyTestNet'
        option encryption none

config wifi-iface 'sta'
       option device radio0
       option network sta
       option mode sta
       option ssid TestNet-5G
       option encryption psk2
       option key 12345

This change updates current_mode structure based on configured hw_mode
received from wpa_supplicant. Also prepare rates table after frequency
selection.

Signed-off-by: Abhilash Tuse <Abhilash.Tuse@imgtec.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name> [cleanup, patch refresh]