Reduce the runtime stack size in BL stages.

This patch separates the stack size for each BL stage and
reduces it after stack usage analysis was done.

Fixes ARM-software/tf-issues#200

Change-Id: I8edc6de2551b0a6788761d121937692b2149bb29

plat/fvp/include/platform_def.h

@@ -45,7 +45,17 @@
  ******************************************************************************/
 
 /* Size of cacheable stacks */
-#define PLATFORM_STACK_SIZE	0x800
+#if DEBUG_XLAT_TABLE
+#define PLATFORM_STACK_SIZE 0x800
+#elif IMAGE_BL1
+#define PLATFORM_STACK_SIZE 0x440
+#elif IMAGE_BL2
+#define PLATFORM_STACK_SIZE 0x400
+#elif IMAGE_BL31
+#define PLATFORM_STACK_SIZE 0x400
+#elif IMAGE_BL32
+#define PLATFORM_STACK_SIZE 0x440
+#endif
 
 #define FIRMWARE_WELCOME_STR		"Booting trusted firmware boot loader stage 1\n\r"