AP MLD: Fix missing check for legacy client case

The AP MLD case missed the "else" branch which handles legacy STA's
disassociation. So this STA's sta_info will not be cleared ever.

Add the "else" check to make sure the sta_info gets cleared.

Fixes: 7ceafb6e9f ("AP MLD: Handle disassociation notification with SME offload to driver")
Signed-off-by: Chenming Huang <quic_chenhuan@quicinc.com>

src/ap/drv_callbacks.c

@@ -1006,6 +1006,8 @@ void hostapd_notif_disassoc(struct hostapd_data *hapd, const u8 *addr)
 					break;
 				}
 			}
+		} else if (!sta->mld_info.mld_sta) {
+			goto legacy;
 		}
 		if (!sta) {
 			wpa_printf(MSG_DEBUG,