staging: wilc1000: make del_virtual_intf static

This patch makes del_virtual_intf static. This function is used only at
wilc_wfi_cfgoperation.c file.
Signed-off-by: Chaehyun Lim <chaehyun.lim@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/wilc1000/wilc_wfi_cfgoperations.c

@@ -3362,7 +3362,7 @@ struct wireless_dev *add_virtual_intf(struct wiphy *wiphy, const char *name,
  *  @date	01 JUL 2012
  *  @version	1.0
  */
-int del_virtual_intf(struct wiphy *wiphy, struct wireless_dev *wdev)
+static int del_virtual_intf(struct wiphy *wiphy, struct wireless_dev *wdev)
 {
 	PRINT_D(HOSTAPD_DBG, "Deleting virtual interface\n");
 	return 0;