Implement a leaner printf for Trusted Firmware

This patch implements a "tf_printf" which supports only the commonly
used format specifiers in Trusted Firmware, which uses a lot less
stack space than the stdlib printf function.

Fixes ARM-software/tf-issues#116

Change-Id: I7dfa1944f4c1e634b3e2d571f49afe02d109a351
diff --git a/bl31/bl31_main.c b/bl31/bl31_main.c
index d949a08..031799c 100644
--- a/bl31/bl31_main.c
+++ b/bl31/bl31_main.c
@@ -34,9 +34,9 @@
 #include <bl_common.h>
 #include <bl31.h>
 #include <context_mgmt.h>
+#include <debug.h>
 #include <platform.h>
 #include <runtime_svc.h>
-#include <stdio.h>
 #include <string.h>
 
 /*******************************************************************************
@@ -77,7 +77,7 @@
 	/* Perform platform setup in BL1 */
 	bl31_platform_setup();
 
-	printf("BL31 %s\n\r", build_message);
+	tf_printf("BL31 %s\n\r", build_message);
 
 	/* Initialise helper libraries */
 	bl31_lib_init();