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

Implement the stream output operator<<() for the PixelFormat and
V4L2PixelFormat 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_pixelformat.h

@@ -8,6 +8,7 @@
 
 #pragma once
 
+#include <ostream>
 #include <stdint.h>
 #include <string>
 
@@ -50,4 +51,6 @@ private:
 	uint32_t fourcc_;
 };
 
+std::ostream &operator<<(std::ostream &out, const V4L2PixelFormat &f);
+
 } /* namespace libcamera */