Staging: wlan-ng: still setting wrong data

In commit 1ca1a92c "Staging: wlan-ng: memsetting the wrong amount of
data" I changed the code so we didn't memset() past the end of the
msg1.bssid.data[] array.  Walter Harms noticed that it was weird that
we were setting the len to 6 when there were 7 elements in the array.
Pavel Roskin pointed out that the intent of the code was actually to
memset() msg1.bssid.data.data[] which is a 6 character array.

Reported-by: Walter Harms <wharms@bfs.de>
Reported-by: Pavel Roskin <proski@gnu.org>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>