media: dt-bindings: media: Document data-enable-active property

Add 'data-enable-active' property to endpoint node properties list.

The property allows to specify the polarity of the data-enable signal,
which when in active state determinates when data lines have to sampled
for valid pixel data.
Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

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

@@ -113,6 +113,8 @@ Optional endpoint properties
   Note, that if HSYNC and VSYNC polarities are not specified, embedded
   synchronization may be required, where supported.
 - data-active: similar to HSYNC and VSYNC, specifies data line polarity.
+- data-enable-active: similar to HSYNC and VSYNC, specifies the data enable
+  signal polarity.
 - field-even-active: field signal level during the even field data transmission.
 - pclk-sample: sample data on rising (1) or falling (0) edge of the pixel clock
   signal.