of/mips: Add device tree support to MIPS

Add the ability to enable CONFIG_OF on the MIPS architecture.

Signed-off-by: Dezhong Diao <dediao@cisco.com>
[grant.likely@secretlab.ca: cleared out obsolete hooks,
	removed ARCH_HAS_DEVTREE_MEM,
	remove __init tags from header file,
	removed debugfs support hunk]
[ddaney@linux-mips.org: backed out over aggressive trimming of hooks]
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Tested-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

arch/mips/kernel/setup.c

@@ -31,6 +31,7 @@
 #include <asm/setup.h>
 #include <asm/smp-ops.h>
 #include <asm/system.h>
+#include <asm/prom.h>
 
 struct cpuinfo_mips cpu_data[NR_CPUS] __read_mostly;
 
@@ -487,6 +488,7 @@ static void __init arch_mem_init(char **cmdline_p)
 	}
 
 	bootmem_init();
+	device_tree_init();
 	sparse_init();
 	paging_init();
 }