[POWERPC] ps3: system bus minor mmio fix

Fix two minor bugs in the PS3 system bus mmio region code.  First, on error or
when freeing a region, retain the bus_addr and len fields to allow subsequent
calls to create the region.  Second, correct the region address argument to the
lv1_unmap_device_mmio_region() call.

Fixes modprobe/rmmod of some drivers.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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>