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/libcamera/stream.cpp

@@ -127,7 +127,7 @@ std::vector<PixelFormat> StreamFormats::pixelformats() const
  *
  * \return A list of frame sizes or an empty list on error
  */
-std::vector<Size> StreamFormats::sizes(PixelFormat pixelformat) const
+std::vector<Size> StreamFormats::sizes(const PixelFormat &pixelformat) const
 {
 	/*
 	 * Sizes to try and extract from ranges.
@@ -240,7 +240,7 @@ std::vector<Size> StreamFormats::sizes(PixelFormat pixelformat) const
  *
  * \return A range of valid image sizes or an empty range on error
  */
-SizeRange StreamFormats::range(PixelFormat pixelformat) const
+SizeRange StreamFormats::range(const PixelFormat &pixelformat) const
 {
 	auto const it = formats_.find(pixelformat);
 	if (it == formats_.end())