If macro WLAN_FEATURE_11BE_MLO is enable, get_station_stats_cb for
TYPE_STATION_STATS is called only if last_req->ml_vdev_info.ml_vdev_count
none zero when WMI_UPDATE_STATS_EVENTID event comes back.
This causes timeout and fail to get station stats for legacy device or for
MLO device which does not set last_req->ml_vdev_info.ml_vdev_count.
To resolve this issue, add sanity check legacy device before invoking the
callback and set last_req->ml_vdev_info.ml_vdev_count if it is MLO device.
Change-Id: I8ca325482fc32de87cbedcba7d4af17d3876cbbc
CRs-Fixed: 3202588