libcamera: v4l2_videodevice: Make V4L2PixelFormat constructor explicit

To achieve the goal of preventing unwanted conversion between a DRM and
a V4L2 FourCC, make the V4L2PixelFormat constructor that takes an
integer value explicit. All users of V4L2 pixel formats flagged by the
compiler are fixed.

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

src/libcamera/include/v4l2_videodevice.h

@@ -157,7 +157,7 @@ public:
 	{
 	}
 
-	V4L2PixelFormat(uint32_t fourcc)
+	explicit V4L2PixelFormat(uint32_t fourcc)
 		: fourcc_(fourcc)
 	{
 	}