libc: Move tf_printf and tf_snprintf to libc

Change their names to printf and snprintf. They are much smaller than
the previous versions we had, which makes them better suited for the
Trusted Firmware.

Change-Id: Ia872af91b7b967c47fce012eccecede7873a3daf
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>
diff --git a/common/tf_log.c b/common/tf_log.c
index 54c0a43..6da1e85 100644
--- a/common/tf_log.c
+++ b/common/tf_log.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2017-2018, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -36,11 +36,11 @@
 
 	prefix_str = plat_log_get_prefix(log_level);
 
-	if (prefix_str != NULL)
-		tf_string_print(prefix_str);
+	while (*prefix_str)
+		putchar(*prefix_str++);
 
 	va_start(args, fmt);
-	tf_vprintf(fmt+1, args);
+	vprintf(fmt + 1, args);
 	va_end(args);
 }