staging: r8188eu: convert rtw_p2p_get_op_ch to return void

rtw_p2p_get_op_ch always returns 0 and it's return value is not used.
Convert it to return void.
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Abdun Nihaal <abdun.nihaal@gmail.com>
Link: https://lore.kernel.org/r/c94caa66e738f254b7b1d967b3016975aa0df5d0.1643466748.git.abdun.nihaal@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/r8188eu/os_dep/ioctl_linux.c

@@ -2580,12 +2580,11 @@ static void rtw_p2p_get_groupid(struct net_device *dev,
 	wrqu->data.length = strlen(extra);
 }
 
-static int rtw_p2p_get_op_ch(struct net_device *dev,
-			       struct iw_request_info *info,
-			       union iwreq_data *wrqu, char *extra)
+static void rtw_p2p_get_op_ch(struct net_device *dev,
+			      struct iw_request_info *info,
+			      union iwreq_data *wrqu, char *extra)
 
 {
-	int ret = 0;
 	struct adapter *padapter = (struct adapter *)rtw_netdev_priv(dev);
 	struct wifidirect_info *pwdinfo = &padapter->wdinfo;
 
@@ -2593,7 +2592,6 @@ static int rtw_p2p_get_op_ch(struct net_device *dev,
 
 	sprintf(extra, "\n\nOp_ch =%.2d\n", pwdinfo->operating_channel);
 	wrqu->data.length = strlen(extra);
-	return ret;
 }
 
 static int rtw_p2p_get_wps_configmethod(struct net_device *dev,