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>

drivers/ram/stm32mp1/stm32mp1_ram.c

@@ -6,6 +6,7 @@
 #include <common.h>
 #include <clk.h>
 #include <dm.h>
+#include <init.h>
 #include <ram.h>
 #include <regmap.h>
 #include <syscon.h>