arc: use unflatten_and_copy_device_tree

Use the common unflatten_and_copy_device_tree to copy the built-in FDT
out of init section.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Acked-by: Vineet Gupta <vgupta@synopsys.com>
Acked-by: Grant Likely <grant.likely@linaro.org>

diff --cc arch/arc/include/asm/mach_desc.h
Simple merge

diff --cc arch/arc/kernel/devtree.c
Simple merge

diff --cc arch/arc/kernel/setup.c
Simple merge