ARM: dts: imx6dl-yapp4: Enable the I2C3 bus on all board variants

imx6dl-yapp4 Draco and Ursa boards use the I2C3 bus to control some
external devices through the /dev files.

So enable the I2C3 bus on all board variants, not just on Hydra.

Signed-off-by: Michal Vokáč <michal.vokac@ysoft.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>