staging: vc04_services: Use vc-sm-cma to support zero copy

staging: vc04_services: Use vc-sm-cma to support zero copy

With the vc-sm-cma driver we can support zero copy of buffers between
the kernel and VPU. Add this support to vchiq-mmal.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.org>
staging: vc-sm-cma: Use a void* pointer as the handle within the kernel

The driver was using an unsigned int as the handle to the outside world,
and doing a nasty cast to the struct dmabuf when handed it back.
This breaks badly with a 64 bit kernel where the pointer doesn't fit
in an unsigned int.

Switch to using a void* within the kernel. Reality is that it is
a struct dma_buf*, but advertising it as such to other drivers seems
to encourage the use of it as such, and I'm not sure on the implications
of that.

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