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>

include/init.h

@@ -106,6 +106,9 @@ int dram_init(void);
  */
 int dram_init_banksize(void);
 
+long get_ram_size(long *base, long size);
+phys_size_t get_effective_memsize(void);
+
 /**
  * arch_reserve_stacks() - Reserve all necessary stacks
  *