[POWERPC] 83xx: Cleaning up machine probing and board initcalls

Cleaned up the probing functionality to be more consistent across all 83xx
boards and added machine_is() protection around board initcalls to ensure they
only do something if we are actually running on that board.

Additionally, removed some dead code on mpc832x_mds.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
diff --git a/arch/powerpc/platforms/83xx/mpc8313_rdb.c b/arch/powerpc/platforms/83xx/mpc8313_rdb.c
index c3b98c3..32e9e94 100644
--- a/arch/powerpc/platforms/83xx/mpc8313_rdb.c
+++ b/arch/powerpc/platforms/83xx/mpc8313_rdb.c
@@ -74,16 +74,9 @@
  */
 static int __init mpc8313_rdb_probe(void)
 {
-	char *model = of_get_flat_dt_prop(of_get_flat_dt_root(),
-					  "model", NULL);
-	if (model == NULL)
-		return 0;
-	if (strcmp(model, "MPC8313ERDB"))
-		return 0;
+        unsigned long root = of_get_flat_dt_root();
 
-	DBG("MPC8313 RDB found\n");
-
-	return 1;
+        return of_flat_dt_is_compatible(root, "MPC8313ERDB");
 }
 
 define_machine(mpc8313_rdb) {