At a node for the axp209, and where necessary the i2c controller to the dts
for various boards. Note the axp209 regulators are omitted as we don't have
any use for them yet, and on some boards were not sure how exactly they are
wired up.

Adding support for just the axp209 without the regulators is still useful, as
it will give us power-button and poweroff support.
Signed-off-by: Carlo Caione <carlo@caione.org>
[hdegoede@redhat.com: Drop the regulator bits for now]
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>