ARC: make a copy of flat DT

The flat DT (currently embedded in vmlinux) is in .init section.
The unflattened/binary tree doesn't copy strings through and references
them from orig flat DT - which could cause catestrohpy if of_* APIs are
called post init, say from a driver which is a loadable module.

Reported-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
diff --git a/arch/arc/kernel/setup.c b/arch/arc/kernel/setup.c
index e591c6a..dc0f968 100644
--- a/arch/arc/kernel/setup.c
+++ b/arch/arc/kernel/setup.c
@@ -354,6 +354,8 @@
 
 	setup_arch_memory();
 
+	/* copy flat DT out of .init and then unflatten it */
+	copy_devtree();
 	unflatten_device_tree();
 
 	/* Can be issue if someone passes cmd line arg "ro"