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>

include/asm-sparc/prom.h

@@ -20,6 +20,9 @@
 #include <linux/proc_fs.h>
 #include <asm/atomic.h>
 
+#define OF_ROOT_NODE_ADDR_CELLS_DEFAULT	2
+#define OF_ROOT_NODE_SIZE_CELLS_DEFAULT	1
+
 typedef u32 phandle;
 typedef u32 ihandle;