common: Move RAM-sizing functions to init.h

These functions relate to memory init so move them into the init
header.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/board/armltd/integrator/integrator.c b/board/armltd/integrator/integrator.c
index 5cdf790..1a472f5 100644
--- a/board/armltd/integrator/integrator.c
+++ b/board/armltd/integrator/integrator.c
@@ -20,6 +20,7 @@
 #include <cpu_func.h>
 #include <dm.h>
 #include <env.h>
+#include <init.h>
 #include <netdev.h>
 #include <asm/io.h>
 #include <dm/platform_data/serial_pl01x.h>