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/timll/devkit3250/devkit3250.c b/board/timll/devkit3250/devkit3250.c
index a4b963d..b455844 100644
--- a/board/timll/devkit3250/devkit3250.c
+++ b/board/timll/devkit3250/devkit3250.c
@@ -6,6 +6,7 @@
  */
 
 #include <common.h>
+#include <init.h>
 #include <asm/arch/sys_proto.h>
 #include <asm/arch/clk.h>
 #include <asm/arch/cpu.h>