The mv643xx ethernet controller limits the packet size for the TX
checksum offloading. This patch sets this limits for Kirkwood and
Dove which have smaller limits that the default.

As a side note, this patch is an updated version of a patch sent some years
ago: http://lists.infradead.org/pipermail/linux-arm-kernel/2010-June/017320.html
which seems to have been lost.
Signed-off-by: NArnaud Patard <arnaud.patard@rtp-net.org>
Signed-off-by: NJason Cooper <jason@lakedaemon.net>
Cc: <stable@vger.kernel.org>