Simplify EGLImageFactory and remove caching logic for now

The platforms that would most benefit (embedded V4L2 decoders)
either don't use frame pooling or don't synchronize with
modified DMA-BUFs unless eglCreateImage() is called each time.

app/streaming/video/ffmpeg-renderers/renderer.h

@@ -502,7 +502,7 @@ public:
     }
 
     // Free the resources allocated during the last `exportEGLImages` call
-    virtual void freeEGLImages(EGLDisplay, EGLImage[EGL_MAX_PLANES]) {}
+    virtual void freeEGLImages() {}
 #endif
 
 #ifdef HAVE_DRM