[POWERPC] ps3: repository storage support

Handle storage-related repository data:
  - Add missing implementations of ps3_repository_read_stor_*() repository
    accessors.
  - Dump storage properties in debug mode
  - Add PS3_DEV_TYPE_STOR_{DISK,ROM,FLASH} device types (which are identical to
    the corresponding SCSI device types) to enum ps3_dev_type

Signed-off-by: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
Signed-off-by: Geoff Levand <geoffrey.levand@am.sony.com>
Acked-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>