powerpc/44x: Migrate Rainier support to ppc44x_simple

Migrate the AMCC Rainier board to use the ppc44x_simple platform file.

Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
diff --git a/arch/powerpc/platforms/44x/Kconfig b/arch/powerpc/platforms/44x/Kconfig
index 66d4499..89e7f1f 100644
--- a/arch/powerpc/platforms/44x/Kconfig
+++ b/arch/powerpc/platforms/44x/Kconfig
@@ -60,6 +60,7 @@
 	bool "Rainier"
 	depends on 44x
 	default n
+	select PPC44x_SIMPLE
 	select 440GRX
 	select PCI
 	help