staging: bcm2835-camera: Remove V4L2/MMAL buffer remapping

The MMAL and V4L2 buffers had been disassociated, and linked on
demand.  Seeing as both are finite and low in number, and we now have
the same number of each, link them for the duration.  This removes the
complexity of maintaining lists as the struct mmal_buffer context
comes back from the VPU, so we can directly link back to the relevant
V4L2 buffer.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.org>
Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>