media: dt-bindings: Add property to describe CSI-2 C-PHY line orders

Each data lane on a CSI-2 C-PHY bus uses three phase encoding and is
constructed from three physical wires. The wires are referred to as A, B
and C and their default order is ABC. However to ease hardware design
the specification allows for the wires to be switched in any order.

Add a vendor neutral property to describe the line order used. The
property name 'line-orders', the possible values it can be assigned and
there names are taken from the MIPI Discovery and Configuration (DisCo)
Specification for Imaging.

Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>