Merge branch 'drop_monitor-Better-sanitize-notified-packets'

Ido Schimmel says:

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drop_monitor: Better sanitize notified packets

When working in 'packet' mode, drop monitor generates a notification
with a potentially truncated payload of the dropped packet. The payload
is copied from the MAC header, but I forgot to check that the MAC header
was set, so do it now.

Patch #1 sets the offsets to the various protocol layers in netdevsim,
so that it will continue to work after the MAC header check is added to
drop monitor in patch #2.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>