Test: Change printf to TEST_LOG

Replace all the 'printf' call to 'TEST_LOG', and use
'tfm_log_printf' instead of standard library 'printf'.

Change-Id: Ie43009cf7ab35fe1fcd07500f41cf83129c37792
Signed-off-by: Mingyang Sun <mingyang.sun@arm.com>
diff --git a/test/framework/test_framework_helpers.c b/test/framework/test_framework_helpers.c
index 7423325..5158c53 100644
--- a/test/framework/test_framework_helpers.c
+++ b/test/framework/test_framework_helpers.c
@@ -70,5 +70,5 @@
 
 void printf_set_color(enum serial_color_t color_id)
 {
-    printf("\33[3%dm", color_id);
+    TEST_LOG("\33[3%dm", color_id);
 }