staging: rtl8712: avoid a useless call to memset().

In r8711_wx_get_wap(), make sure we do not call memcpy() on a memory area that
has just been zeroed by a call to memset().

Signed-off-by: Cyril Roelandt <tipecaml@gmail.com>
Acked-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>