[ETH1394]: Fix unaligned accesses.

Several u64 objects are derefernced in situations where the
pointer is not guarenteed to be aligned correctly.  Use
get_unaligned() as needed.

Thanks to Will Simoneau for lots of testing and debugging
help.

Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Stefan Richter <stefanr@s5r6.in-berlin.de>