metag: of_platform_populate from arch generic code

If no init_machine callback is provided, call of_platform_populate()
instead. This allows a board/SoC that only needs to call
of_platform_populate to omit the callback altogether.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Rob Herring <rob.herring@calxeda.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: devicetree-discuss@lists.ozlabs.org

arch/metag/kernel/setup.c

@@ -20,6 +20,7 @@
 #include <linux/memblock.h>
 #include <linux/mm.h>
 #include <linux/of_fdt.h>
+#include <linux/of_platform.h>
 #include <linux/pfn.h>
 #include <linux/root_dev.h>
 #include <linux/sched.h>
@@ -424,6 +425,9 @@ static int __init customize_machine(void)
 	/* customizes platform devices, or adds new ones */
 	if (machine_desc->init_machine)
 		machine_desc->init_machine();
+	else
+		of_platform_populate(NULL, of_default_bus_match_table, NULL,
+				     NULL);
 	return 0;
 }
 arch_initcall(customize_machine);