batman-adv: fix compilation bug in batadv_is_cfg80211_netdev()

[mrnuke]

Maintainer: @simonwunderlich @ecsv Compile tested: bcm2711 Run tested: bcm2711, start batman, enjoy a warning-free dmesg

Description:

Because batman-adv is built under backports, not a clean linux tree, the CONFIG_CFG80211 does not exist. The evaluation of IS_ENABLED() in batadv_is_cfg80211_netdev() will be false, causing the funtion to always return false.

This means that the wifi_flags of an interface don't get set, causing batadv_is_wifi_hardif() to always return false. As a result, batadv_v_elp_get_throughput() never tries to get the station info from cfg80211, resulting in the following warning:

batman_adv: bat0: WiFi driver or ethtool info does not provide
information about link speeds on interface phy1-mesh0,
therefore defaulting to hardcoded throughput values of 1.0 Mbps.

So replace CONFIG_CFG80211 with CPTCFG_CFG80211, which is the correct macro to use under backports.

[ecsv]

Thanks, the idea behind the patch looks good and correct. But you need to make sure that the patch:

• can be applied via git-am - special requirement for my workflow
• has no modifications after running make package/batman-adv/{clean,refresh} - requirement for the whole openwrt-routing repository

Both are not the case here. The patch look more like:

From: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Date: Thu, 6 Apr 2023 18:05:50 -0500
Subject: fix batadv_is_cfg80211_netdev

--- a/net/batman-adv/hard-interface.c
+++ b/net/batman-adv/hard-interface.c
@@ -307,8 +307,7 @@ static bool batadv_is_cfg80211_netdev(st
 {
    if (!net_device)
        return false;
-
-#if IS_ENABLED(CONFIG_CFG80211)
+#if IS_ENABLED(CPTCFG_CFG80211)
    /* cfg80211 drivers have to set ieee80211_ptr */
    if (net_device->ieee80211_ptr)
        return true;

And of course, the name of the patch must then also be changed to 0005-fix-batadv_is_cfg80211_netdev.patch (which is the name used by git-format-patch for this subject)