wlan-ng: add a bounds check

I'm not sure where these results come from, but it can't hurt to
add a sanity check the array offset.  The .results[] array on the
next line has HFA384x_CHINFORESULT_MAX (16) elements.

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