Handle corrupt AMI message more gracefully

For some reason, AMI can send incomplete AMI messages.  This could be
because they are too big or perhaps the packet got corrupt.  Either way,
now we don't blow up.

Change-Id: Ifdac7e812012d79bcbae4043c2e08f0c03fd8b8c
Signed-off-by: Paul Belanger <paul.belanger@polybeacon.com>