x86 romstage: Move stack just below RAMTOP

Placement of romstage stack in RAM was vulnerable for getting corrupted
by decompressed ramstage.

Change-Id: Ic032bd3e69f4ab8dab8e5932df39fab70aa3e769
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/7096
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@google.com>

src/arch/x86/init/crt0_romcc_epilogue.inc

@@ -11,7 +11,7 @@ __main:
 	post_code(POST_PREPARE_RAMSTAGE)
 	cld			/* clear direction flag */
 
-	movl $ROMSTAGE_STACK, %esp
+	movl $CONFIG_RAMTOP, %esp
 	movl	%esp, %ebp
 	call copy_and_run
 

src/arch/x86/init/prologue.inc

@@ -18,7 +18,6 @@
  */
 
 #include <cpu/x86/post_code.h>
-#include <cpu/x86/stack.h>
 
 .section ".rom.data", "a", @progbits
 .section ".rom.text", "ax", @progbits