arm64: dts: hisilicon: hi3670.dtsi: add I2C settings

The I2C buses are not declared at the device tree. As this will
be needed by further patches, add them, keeping all in
disabled state. Per-board settings can override it.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Wei Xu <xuwei5@hisilicon.com>