libcamera: control_serializer: Initialize serial_

The ControlSerializer::serial_ member variable isn't initialized. Add a
constructor to the class to initialize it.

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

src/libcamera/include/control_serializer.h

@@ -20,6 +20,8 @@ class ByteStreamBuffer;
 class ControlSerializer
 {
 public:
+	ControlSerializer();
+
 	void reset();
 
 	static size_t binarySize(const ControlInfoMap &info);