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/compulab/cm_t43/spl.c b/board/compulab/cm_t43/spl.c
index 7da9a9a..fdab9c3 100644
--- a/board/compulab/cm_t43/spl.c
+++ b/board/compulab/cm_t43/spl.c
@@ -4,6 +4,7 @@
  */
 
 #include <common.h>
+#include <init.h>
 #include <spl.h>
 #include <i2c.h>
 #include <asm/arch/clock.h>