libcamera: PixelFormat: Mark all function arguments of type PixelFormat as const reference

PixelFormat was previously an alias for unsigned int but is now a
class. Make all functions taking PixelFormat do so as a const reference.

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

src/qcam/viewfinder.cpp

@@ -44,8 +44,8 @@ QImage ViewFinder::getCurrentImage()
 	return image_->copy();
 }
 
-int ViewFinder::setFormat(libcamera::PixelFormat format, unsigned int width,
-			  unsigned int height)
+int ViewFinder::setFormat(const libcamera::PixelFormat &format,
+			  unsigned int width, unsigned int height)
 {
 	int ret;