wlan-ng: replace calls to kmalloc and memcpy with kmemdup

This patch replaces calls to kmalloc that are followed
by memcpy with calls to kmemdup.
This patch was found using coccicheck with api/memdup.cocci,
with memdup.cocci script slightly altered in the following way:

@depends on patch@
expression from,to,size,flag;
position p != {r1.p,r2.p};
@@

-  to = \(kmalloc@p\|kzalloc@p\)(size,flag);
+  to = kmemdup(from,size,flag);
-  memcpy(to, from, size);

Signed-off-by: Xenia Ragiadakou <burzalodowa@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>