libcamera: controls: Add a set of initial controls

Add an initial set of controls to demonstrate how controls are defined.

Proper documentation for each control is missing.

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

include/libcamera/control_ids.h

@@ -13,6 +13,12 @@
 namespace libcamera {
 
 enum ControlId {
+	AwbEnable,
+	Brightness,
+	Contrast,
+	Saturation,
+	ManualExposure,
+	ManualGain,
 };
 
 } /* namespace libcamera */