Revert "staging: bcm2835_camera: Ensure all buffers are returned on disable"

This reverts commit d70c57a7c6a069977a0d827e1d5e2de53fb87e6d.

The patch has mutated beyond recognition and created merge errors
against 37c35be "staging: mmal-vchiq: Add support for event callbacks."

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>