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/cmd/ti/ddr3.c b/cmd/ti/ddr3.c
index 5513089..a452fe7 100644
--- a/cmd/ti/ddr3.c
+++ b/cmd/ti/ddr3.c
@@ -6,6 +6,7 @@
  */
 
 #include <cpu_func.h>
+#include <init.h>
 #include <asm/arch/hardware.h>
 #include <asm/cache.h>
 #include <asm/emif.h>