[POWERPC] PS3: System-bus rework

Rework the PS3 system bus to unify device support.
 - DMA region sizes must be a power of two
 - storage bus DMA updates:
  - Small fixes for the PS3 DMA core:
      o fix alignment bug
      o kill superfluous test
      o indentation
      o spelling
      o export ps3_dma_region_{create,free}()
  - ps3_dma_region_init():
      o Add `addr' and `len' parameters, so you can create a DMA region that
        does not cover all memory (use `NULL' and `0' to cover all memory).
	This is needed because there are not sufficient IOMMU resources to have
	all DMA regions cover all memory.
      o Uninline
  - Added remove and shutdown routines to all drivers.
  - Added loadable module support to all drivers.
  - Added HV calls for iopte management (needed by sound driver).

Signed-off-by: MOKUNO Masakazu <mokuno@sm.sony.co.jp>
Signed-off-by: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
Signed-off-by: Geoff Levand <geoffrey.levand@am.sony.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>