add special init code for EOS D30 cameras. simplified canon_usb_camera_init(). moved stuff from canon_usb_ready() to canon_usb_init(). git-svn-id: https://svn.code.sf.net/p/gphoto/code/trunk/libgphoto2@3518 67ed7778-7388-44ab-90cf-0a291f65f57c