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/ids/ids8313/ids8313.c b/board/ids/ids8313/ids8313.c
index 2b6e4df..6e74e93 100644
--- a/board/ids/ids8313/ids8313.c
+++ b/board/ids/ids8313/ids8313.c
@@ -13,6 +13,7 @@
 
 #include <common.h>
 #include <fdt_support.h>
+#include <init.h>
 #include <mpc83xx.h>
 #include <spi.h>
 #include <linux/libfdt.h>