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/siemens/corvus/board.c b/board/siemens/corvus/board.c
index a569bd5..0376820 100644
--- a/board/siemens/corvus/board.c
+++ b/board/siemens/corvus/board.c
@@ -12,6 +12,7 @@
 
 #include <common.h>
 #include <dm.h>
+#include <init.h>
 #include <asm/io.h>
 #include <asm/arch/at91sam9g45_matrix.h>
 #include <asm/arch/at91sam9_smc.h>