libcamera: Add operator<<() for V4L2 format classes

Implement the stream output operator<<() for the V4L2DeviceFormat and
V4L2SubdeviceFormat classes to simplify printing them.

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

include/libcamera/internal/v4l2_subdevice.h

@@ -9,6 +9,7 @@
 
 #include <memory>
 #include <optional>
+#include <ostream>
 #include <string>
 #include <vector>
 
@@ -35,6 +36,8 @@ struct V4L2SubdeviceFormat {
 	uint8_t bitsPerPixel() const;
 };
 
+std::ostream &operator<<(std::ostream &out, const V4L2SubdeviceFormat &f);
+
 class V4L2Subdevice : public V4L2Device
 {
 public:

include/libcamera/internal/v4l2_videodevice.h

@@ -11,6 +11,7 @@
 #include <atomic>
 #include <memory>
 #include <optional>
+#include <ostream>
 #include <stdint.h>
 #include <string>
 #include <vector>
@@ -180,6 +181,8 @@ public:
 	const std::string toString() const;
 };
 
+std::ostream &operator<<(std::ostream &out, const V4L2DeviceFormat &f);
+
 class V4L2VideoDevice : public V4L2Device
 {
 public: