More consistent SA check for unexpected Data frames

More consistent SA check for unexpected Data frames

Use the same rules for dropping driver notifications for Data frames
from unassociated stations as were added for Management frame reception.
This results in more consistent behavior in sending out Deauthentication
frames with Reason Code 6/7.

This case was already checking for unexpected multicast addresses, so
there was no issue for the PMF protections for unexpected disconnection.
Anyway, better avoid unnecessary Deauthentication frames consistently.

Signed-off-by: Jouni Malinen <j@w1.fi>