rockchip: i2c: Add compatibles for Rockchip Cortex-A9 socs

The Cortex-A9 socs rk3066 and rk3188 share the IP but have their own
compatible values, so add them to make the i2c on these platforms accessible.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Acked-by: Simon Glass <sjg@chromium.org>