libcamera: v4l2_videodevice: Cache PixelFormatInfo

Cache the PixelFormatInfo instead of looking it up in every call to
createBuffer(). This prepares for usage of the info in queueBuffer(), to
avoid a looking every time a buffer is queued.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Hirokazu Honda <hiroh@chromium.org>

include/libcamera/internal/v4l2_videodevice.h

@@ -241,6 +241,7 @@ private:
 
 	V4L2Capability caps_;
 	V4L2DeviceFormat format_;
+	const PixelFormatInfo *formatInfo_;
 
 	enum v4l2_buf_type bufferType_;
 	enum v4l2_memory memoryType_;