mtd/ps3vram: Add ps3vram driver for accessing video RAM as MTD
Add ps3vram driver, which exposes unused video RAM on the PS3 as a MTD
device suitable for storage or swap. Fast data transfer is achieved
using a local cache in system RAM and DMA transfers via the GPU.
Signed-off-by: Vivien Chappelier <vivien.chappelier@free.fr> Signed-off-by: Jim Paris <jim@jtan.com> Acked-by: Geoff Levand <geoffrey.levand@am.sony.com> Acked-by: David Woodhouse <David.Woodhouse@intel.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>