Staging: rar and memrar updates

rar: perform a clean up pass

- Move to a registration model where each RAR is claimed/unclaimed
- Use that to fix the client stuff (one client per RAR so no need to queue stuff)
- Support unregister so drivers can rmmod themselves safely
- Fix locking hang on calling rar lock from rar callback
- Clean up
- Kerneldoc

Folded in the memrar update as Greg asked

- Fix various unload related bugs
- Use the per RAR allocator/deallocator
- Add kerneldoc

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>