rm obsolete DHCP netmask

Author: Jason2866

libraries/WiFi/src/WiFiGeneric.cpp

@@ -191,16 +191,6 @@ esp_err_t set_esp_interface_ip(esp_interface_t interface, IPAddress local_ip=IPA
         lease.start_ip.addr = _byte_swap32(lease.start_ip.addr);
         lease.end_ip.addr = _byte_swap32(lease.end_ip.addr);
         log_v("DHCP Server Range: %s to %s", IPAddress(lease.start_ip.addr).toString().c_str(), IPAddress(lease.end_ip.addr).toString().c_str());
-        err = esp_netif_dhcps_option(
-            esp_netif,
-            ESP_NETIF_OP_SET,
-            ESP_NETIF_SUBNET_MASK,
-            (void*)&info.netmask.addr, sizeof(info.netmask.addr)
-        );
-		if(err){
-        	log_e("DHCPS Set Netmask Failed! 0x%04x", err);
-        	return err;
-        }
         err = esp_netif_dhcps_option(
             esp_netif,
             ESP_NETIF_OP_SET,