libcamera: ipu3: imgu: Do not cache index

The numerical index of the imgu is only used to create its name in
string form. There is no need to keep it around after that, remove it.

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

src/libcamera/pipeline/ipu3/imgu.cpp

@@ -36,8 +36,7 @@ int ImgUDevice::init(MediaDevice *media, unsigned int index)
 {
 	int ret;
 
-	index_ = index;
-	name_ = "ipu3-imgu " + std::to_string(index_);
+	name_ = "ipu3-imgu " + std::to_string(index);
 	media_ = media;
 
 	/*

src/libcamera/pipeline/ipu3/imgu.h

@@ -67,7 +67,6 @@ public:
 		      bool enable);
 	int enableLinks(bool enable);
 
-	unsigned int index_;
 	std::string name_;
 	MediaDevice *media_;