[PATCH] powerpc: fix RTC/NVRAM accesses on Maple

Due to a firmware device tree bug, RTC and NVRAM accesses (including
halt/reboot) on Maple have been broken since January, when an untested
build fix went in. This code patches the device tree in Linux.

Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com>
Signed-off-by: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>