Start split out of common open firmware code

This creates drivers/of/base.c (depending on CONFIG_OF) and puts
the first trivially common bits from the prom.c files into it.

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Acked-by: Paul Mackerras <paulus@samba.org>
Acked-by: David S. Miller <davem@davemloft.net>
diff --git a/include/asm-powerpc/prom.h b/include/asm-powerpc/prom.h
index 1134aea..9fe0152 100644
--- a/include/asm-powerpc/prom.h
+++ b/include/asm-powerpc/prom.h
@@ -21,6 +21,9 @@
 #include <asm/irq.h>
 #include <asm/atomic.h>
 
+#define OF_ROOT_NODE_ADDR_CELLS_DEFAULT	1
+#define OF_ROOT_NODE_SIZE_CELLS_DEFAULT	1
+
 /* Definitions used by the flattened device tree */
 #define OF_DT_HEADER		0xd00dfeed	/* marker */
 #define OF_DT_BEGIN_NODE	0x1		/* Start of node, full name */