The mv64xxx-i2c embedded in the Armada XP have a new feature to
offload i2c transaction. This new version of the IP come also with
some errata. This lead to the introduction to a another compatible
string.

This commit split the i2c information into armada-370.dtsi and
armada-xp.dtsi. Most of the data remains the same and stay in the
common file Armada-370-xp.dtsi. With this new feature the size of the
registers are bigger for Armada XP and the new compatible string is
used.
Signed-off-by: NGregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: NJason Cooper <jason@lakedaemon.net>