Don't use variables as tf_printf format strings

Using variables as format strings can generate security problems when
the user can control those strings. Some compilers generate warnings
in that cases, even when the variables are constants and are not
controlled by the user.

Change-Id: I65dee1d1b66feab38cbf298290a86fa56e6cca40
Signed-off-by: Roberto Vargas <roberto.vargas@arm.com>

lib/xlat_tables_v2/xlat_tables_internal.c

@@ -1066,18 +1066,19 @@ static void xlat_desc_print(const xlat_ctx_t *ctx, uint64_t desc)
 
 	if (xlat_regime == EL3_REGIME) {
 		/* For EL3, the AP[2] bit is all what matters */
-		tf_printf((desc & LOWER_ATTRS(AP_RO)) ? ro_str : rw_str);
+		tf_printf("%s", (desc & LOWER_ATTRS(AP_RO)) ? ro_str : rw_str);
 	} else {
 		const char *ap_str = (desc & LOWER_ATTRS(AP_RO)) ? ro_str : rw_str;
-		tf_printf(ap_str);
-		tf_printf(priv_str);
+		tf_printf("%s", ap_str);
+		tf_printf("%s", priv_str);
 		/*
 		 * EL0 can only have the same permissions as EL1 or no
 		 * permissions at all.
 		 */
-		tf_printf((desc & LOWER_ATTRS(AP_ACCESS_UNPRIVILEGED))
+		tf_printf("%s",
+			  (desc & LOWER_ATTRS(AP_ACCESS_UNPRIVILEGED))
 			  ? ap_str : no_access_str);
-		tf_printf(user_str);
+		tf_printf("%s", user_str);
 	}
 
 	const char *xn_str = "-XN";
@@ -1085,14 +1086,14 @@ static void xlat_desc_print(const xlat_ctx_t *ctx, uint64_t desc)
 
 	if (xlat_regime == EL3_REGIME) {
 		/* For EL3, the XN bit is all what matters */
-		tf_printf(LOWER_ATTRS(XN) & desc ? xn_str : exec_str);
+		tf_printf("%s", LOWER_ATTRS(XN) & desc ? xn_str : exec_str);
 	} else {
 		/* For EL0 and EL1, we need to know who has which rights */
-		tf_printf(LOWER_ATTRS(PXN) & desc ? xn_str : exec_str);
-		tf_printf(priv_str);
+		tf_printf("%s", LOWER_ATTRS(PXN) & desc ? xn_str : exec_str);
+		tf_printf("%s", priv_str);
 
-		tf_printf(LOWER_ATTRS(UXN) & desc ? xn_str : exec_str);
-		tf_printf(user_str);
+		tf_printf("%s", LOWER_ATTRS(UXN) & desc ? xn_str : exec_str);
+		tf_printf("%s", user_str);
 	}
 
 	tf_printf(LOWER_ATTRS(NS) & desc ? "-NS" : "-S");