Fix a compile error when smoltcp can return more than 1 DNS result (e…

…sp-rs#442)

Update the WifiStack::dns_query() return type to match the type returned
by smoltcp, rather than assuming the result size is always 1.

esp-wifi/src/wifi_interface.rs

@@ -374,7 +374,8 @@ impl<'a, MODE: WifiDeviceMode> WifiStack<'a, MODE> {
         &self,
         name: &str,
         query_type: DnsQueryType,
-    ) -> Result<heapless::Vec<IpAddress, 1>, WifiStackError> {
+    ) -> Result<heapless::Vec<IpAddress, { smoltcp::config::DNS_MAX_RESULT_COUNT }>, WifiStackError>
+    {
         use smoltcp::socket::dns;
 
         match query_type {