ARM: Orion: Set eth packet size csum offload limit

commit 58569aee5a1a5dcc25c34a0a2ed9a377874e6b05 upstream.

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: Arnaud Patard <arnaud.patard@rtp-net.org>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>
[bwh: Backported to 3.2: adjust for the extra two parameters of
 orion_ge0{0,1}_init()]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>