ARM: dts: sun8i: a83t: Add device node for CSI (Camera Sensor Interface)

The A83T SoC has a camera sensor interface (known as CSI in Allwinner
lingo), which is similar to the one found on the A64 and H3. The only
difference seems to be that support of MIPI CSI through a connected
MIPI CSI-2 bridge.

Add a device node for it, and pinctrl nodes for the commonly used MCLK
and 8-bit parallel interface. The property /omit-if-no-ref/ is added to
the pinctrl nodes to keep the device tree blob size down if they are
unused.

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