CBMEM AMD: Fix calls to set_top_of_ram_once()

We can postpone the call to set_top_of_ram_once() outside the
loops and make just one call instead.

As set_top_of_ram() is now only called once, it is no longer
necessary to check if high_tables_base was already set.

Change-Id: I302d9af52ac40c7fa8c7c7e65f82e00b031cd397
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/3895
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/include/cbmem.h

@@ -136,7 +136,7 @@ void cbmem_add_lb_mem(struct lb_memory *mem);
 
 #ifndef __PRE_RAM__
 extern uint64_t high_tables_base, high_tables_size;
-void set_top_of_ram_once(uint64_t ramtop);
+void set_top_of_ram(uint64_t ramtop);
 void set_cbmem_toc(struct cbmem_entry *);
 #endif