libcamera: controls: Define AwbLocked control

Define a control to report the AWB algorithm locking state.
The control definition is copied from the AeLocked one.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>

src/libcamera/control_ids.yaml

@@ -208,6 +208,17 @@ controls:
           value: 7
           description: Maximum allowed value (place any new values above here).
 
+  - AwbLocked:
+      type: bool
+      description: |
+        Report the lock status of a running AWB algorithm.
+
+        If the AWB algorithm is locked the value shall be set to true, if it's
+        converging it shall be set to false. If the AWB algorithm is not
+        running the control shall not be present in the metadata control list.
+
+        \sa AwbEnable
+
   - ColourGains:
       type: float
       description: |