[droidcamsrc] don't unconditionally start the camera device if we are negotiating one pad.
[droidcamsrc] don't unconditionally start the camera device if we are negotiating one pad.

This is a missing part in commit 673e679b4973e0877f7c321115bd58bbc208cdc5

mlehtima/gst-droid,mlehtima/gst-droid,sailfishos/gst-droid