wlan:Check priviledge permission before processing SET_VAR_GET_NONE IOCTL

Kernel assumes all SET IOCTL commands are assigned with even
numbers. But in our WLAN driver, some SET IOCTLS are assigned with
odd numbers. This leads kernel fail to check, for some SET IOCTLs,
whether user has the right permission to do SET operation.
Hence, in driver, before processing SET_VAR_GET_NONE IOCTL, making
sure user task has right permission to process the command.

Change-Id: Icbdfe69c18c1ab3b75d63e046d5251307a794817
CRs-Fixed: 930942
diff --git a/CORE/HDD/src/wlan_hdd_wext.c b/CORE/HDD/src/wlan_hdd_wext.c
index 4999133..8f1412c 100644
--- a/CORE/HDD/src/wlan_hdd_wext.c
+++ b/CORE/HDD/src/wlan_hdd_wext.c
@@ -7606,6 +7606,13 @@
     int apps_args[MAX_VAR_ARGS] = {0};
     int num_args;
 
+    if (!capable(CAP_NET_ADMIN))
+    {
+        VOS_TRACE(VOS_MODULE_ID_HDD, VOS_TRACE_LEVEL_ERROR,
+                  FL("permission check failed"));
+        return -EPERM;
+    }
+
     /* helper function to get iwreq_data with compat handling. */
     if (hdd_priv_get_data(&u_priv_wrqu.data, wrqu))
     {