Instead of ieee80211_bss_get_ie(), use the more typed
ieee80211_bss_get_elem().

Link: https://lore.kernel.org/r/20211220113609.56f8e2a70152.Id5a56afb8a4f9b38d10445e5a1874e93e84b5251@changeidSigned-off-by: Johannes Berg <johannes.berg@intel.com>