net: wireless: rtl8189es: Guard debug function with CONFIG_RTW_DEBUG

The helper function `nl80211_tx_power_setting_str` is only used for
debugging purposes when `CONFIG_RTW_DEBUG` is enabled. When this
config is disabled, the function is defined but not used, causing a
build failure with `-Werror=unused-function`.

Fix this by enclosing the entire function definition within an
`#ifdef CONFIG_RTW_DEBUG` block. This ensures the function is only
compiled when it is actually needed, resolving the build error in a
clean and idiomatic way.

Signed-off-by: Khusika Dhamar Gusti <[email protected]>

Author: khusika

drivers/net/wireless/rtl8189es/os_dep/linux/ioctl_cfg80211.c

@@ -4143,6 +4143,7 @@ static int cfg80211_rtw_disconnect(struct wiphy *wiphy, struct net_device *ndev,
 }
 
 #if (LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 31))
+#ifdef CONFIG_RTW_DEBUG
 static const char *nl80211_tx_power_setting_str(int type)
 {
 	switch (type) {
@@ -4156,6 +4157,7 @@ static const char *nl80211_tx_power_setting_str(int type)
 		return "UNKNOWN";
 	};
 }
+#endif	/*	CONFIG_RTW_DEBUG	*/
 
 static int cfg80211_rtw_set_txpower(struct wiphy *wiphy,
 #if (LINUX_VERSION_CODE >= KERNEL_VERSION(3, 8, 0))