dt-bindings: i2c: maxim,max96712: Require setting bus-type property

The MAX96712 can support both a CSI-2 C-PHY and D-PHY bus. The initial
staging driver however only supported D-PHY and the bus-type property
was left optional.

In preparation for adding C-PHY support to the staging driver make the
bus-type property mandatory as it is needed to select the correct PHY
mode. Without the bus-type property present, the driver falls-back to
D-PHY mode, so the change is functionally backward compatible with old
DTS files lacking the property.

The only in-tree DTS file (renesas/r8a779a0-falcon-csi-dsi.dtsi) that
lacked the property uses D-PHY and have been updated.

Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

Documentation/devicetree/bindings/media/i2c/maxim,max96712.yaml

@@ -65,9 +65,14 @@ properties:
 
             properties:
               data-lanes: true
+              bus-type:
+                enum:
+                  - 1 # MEDIA_BUS_TYPE_CSI2_CPHY
+                  - 4 # MEDIA_BUS_TYPE_CSI2_DPHY
 
             required:
               - data-lanes
+              - bus-type
 
     required:
       - port@4
@@ -82,6 +87,7 @@ additionalProperties: false
 examples:
   - |
     #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/media/video-interfaces.h>
 
     i2c@e6508000 {
             #address-cells = <1>;
@@ -101,6 +107,7 @@ examples:
                             port@4 {
                                     reg = <4>;
                                     max96712_out0: endpoint {
+                                            bus-type = <MEDIA_BUS_TYPE_CSI2_DPHY>;
                                             clock-lanes = <0>;
                                             data-lanes = <1 2 3 4>;
                                             remote-endpoint = <&csi40_in>;