libcamera: v4l2_videodevice: Rename toV4L2Fourcc to toV4L2PixelFormat

Now that the functions return a V4L2PixelFormat, adapt their name
accordingly.

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

test/libtest/buffer_source.cpp

@@ -70,7 +70,8 @@ int BufferSource::allocate(const StreamConfiguration &config)
 	}
 
 	format.size = config.size;
-	format.fourcc = V4L2VideoDevice::toV4L2Fourcc(config.pixelFormat, false);
+	format.fourcc = V4L2VideoDevice::toV4L2PixelFormat(config.pixelFormat,
+							   false);
 	if (video->setFormat(&format)) {
 		std::cout << "Failed to set format on output device" << std::endl;
 		return TestFail;