ARM: dts: sun8i: a83t: Add I2C2 pinmux setting for PE pins

I2C2 is available on the PE pingroup, on the same pins as the camera
sensor interface (CSI) controller's camera control interface pins.
This provides an option to use I2C2 instead of that control interface
to configure camera sensors.

Add a pinctrl node for it. The property /omit-if-no-ref/ is added to
keep the device tree blob size down if it is unused.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>