[media] dt: bindings: Add lane-polarity property to endpoint nodes

Add lane-polarity property to endpoint nodes. This essentially tells that
the order of the differential signal wires is inverted.
Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

Documentation/devicetree/bindings/media/video-interfaces.txt

@@ -106,6 +106,12 @@ Optional endpoint properties
 - link-frequencies: Allowed data bus frequencies. For MIPI CSI-2, for
   instance, this is the actual frequency of the bus, not bits per clock per
   lane value. An array of 64-bit unsigned integers.
+- lane-polarities: an array of polarities of the lanes starting from the clock
+  lane and followed by the data lanes in the same order as in data-lanes.
+  Valid values are 0 (normal) and 1 (inverted). The length of the array
+  should be the combined length of data-lanes and clock-lanes properties.
+  If the lane-polarities property is omitted, the value must be interpreted
+  as 0 (normal). This property is valid for serial busses only.
 
 
 Example