wifi: cfg80211: wext: add extra SIOCSIWSCAN data check

In 'cfg80211_wext_siwscan()', add extra check whether number of
channels passed via 'ioctl(sock, SIOCSIWSCAN, ...)' doesn't exceed
IW_MAX_FREQUENCIES and reject invalid request with -EINVAL otherwise.

Reported-by:  <syzbot+253cd2d2491df77c93ac@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=253cd2d2491df77c93ac


Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Link: https://msgid.link/20240531032010.451295-1-dmantipov@yandex.ru


Signed-off-by: Johannes Berg <johannes.berg@intel.com>