of: Introduce common early_init_dt_scan

Most architectures scan the all the same items early in the FDT and none
are really architecture specific. Create a common early_init_dt_scan to
unify the early scan of root, memory, and chosen nodes in the flattened
DT.

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

include/linux/of_fdt.h

@@ -116,6 +116,8 @@ extern void early_init_dt_setup_initrd_arch(u64 start, u64 end);
 extern int early_init_dt_scan_root(unsigned long node, const char *uname,
 				   int depth, void *data);
 
+extern bool early_init_dt_scan(void *params);
+
 /* Other Prototypes */
 extern void unflatten_device_tree(void);
 extern void unflatten_and_copy_device_tree(void);